Best 10 cloud storage for docs 2017

More than just a tech-friendly buzzword, cloud storage is becoming an integral part of most of our lives, giving us access to our files and data from any device, anywhere in the world.
There's an overwhelming number of companies offering cloud storage though, so how are you meant to pick one? Our buying guide breaks down the best cloud storage services by price, features, storage limits and more, to help you pick the one that's right for you.


Dropbox is one of the only services to offer clients for Linux and Blackberry, alongside the usual Windows, macOS, Android and iOS standards. There's an official Windows Phone app too.
The free Basic account comes with a paltry 2GB of storage. For documents this is huge, but if you want to store any kind of media – photos, music, or video - it will disappear very fast.
You can upgrade to the 1TB plan for £7.99 per month, but Dropbox also offers 500MB of additional free storage for each friend you get to sign up to the service - with a limit of 16GB.
Dropbox works by creating a local folder on your device or PC that then syncs with an online version. This means you have all your data available whether you are on or offline. This doesn't apply to mobile devices, though: you can make select files available offline on your tablet or smartphone, and offline editing is among the best we’ve seen.
Folders and files can also be shared with others but you can’t set permissions on the Basic account, so files can be edited (and even deleted) by other users. The Basic account isn't a total disaster, though, as Dropbox backs up any changes to files for 30 days. So if you need an older version or want to undelete a file, it’s still there.
If you pay £7.99 per month to get the Dropbox Plus account, you will be able to enable read-only permissions as well as setting passwords and expirations for shared links.
Security features include two-step authentication (always worth turning on) and all files held on the Dropbox servers are encrypted by AES 256-bit encryption, albeit employed from Dropbox’s side rather than the user, with SSL for the data being uploaded and downloaded.
Dropbox remains a solid choice for cloud storage. It may lack a few of the whistles and bells of its rivals, but it’s easy to use and compatible with so many applications.

Google Drive

Google Drive is at the heart of the various online services that Google currently offers. You get 15GB of free space when you create a Google account - or link to an existing one. You'll already have a Drive account if you use Gmail, Google Calendar, or even YouTube.
The space is shared across all these services, so if you have large attachments on emails then they will count in the 15GB, and enabling the automatic photo backup to Google+ from a smartphone acts the same way.
There are currently two options for uploading photos and videos. "High quality" is free and doesn't count against your storage but the unmolested "Original" quality versions do. Google Docs, Sheets, Slides, Presentations, Drawings and files that others have shared with you don't count against your allocation either.
Drive works in the same way as most cloud storage solutions: a local folder in Windows is linked to a duplicate cloud version. Versioning is supported, as is real-time collaboration on documents via the Google Docs app.
The old Google Drive app has been replaced by Backup & Sync for Windows and macOS, with mobile versions of Google Drive for Android and iOS. There's selective sync, so you can choose which folders sync on each PC or laptop.
On the whole, the interface across the apps is intuitive, with a basic file tree showing where your stuff is kept. You can choose specific files to be available offline on the mobile versions, and these can be edited - if they were created in Google Docs - then synced when you connect to the internet again. For other formats (such as Word) you’ll need to open them in another app - thus creating a duplicate copy.
Data is encrypted in 128-bit AES rather than the 256-bit employed by Box, OneDrive, and Dropbox. Google asserts that it won’t pry into the content of your Drive folder unless compelled by law enforcement agencies, and you can set up two-step verification on your account to add another layer of security. 
If you live in the Google universe then it really is an excellent storage option.


Opening a new account with pCloud will give you a respectable 10GB of free storage (twice that of OneDrive, and five times Dropbox’s basic offering).
This can be quickly upgraded to 20GB through the regular incentives such as recommending friends (1GB per person) completing a tutorial (3GB) and various social media links, but the real temptation is the very reasonable prices for the larger storage options.
500GB will set you back around £3.90p/m ($4.99), while 2TB (the Premium Plus plan) is available for around £7.80p/m ($9.99).
Thre's also a new Lifetime plan available for £195 ($250), which gets you 2TB of storage and is a one-off payment. It sounds like a lot of money, but could save you a lot of money in the long-run, so if you want a long-term solution it's a good option.
There are clients available for Windows, Mac, Linux, iOS and Android, plus you can also access your account via the website. An iPad app is on the way, but the iPhone app now has a handy auto-delete feature which removes photos from your phone after they are copied to the cloud.
pCloud imposes no file size restrictions, so you can upload anything that your storage space allows. This is done in impressively quick fashion, with syncing proving fast and efficient. All data transfers between the pCloud servers and your machine are handled with TLS/SSL encryption, so they should be safe on their travels. 
There are import options which can automatically transfer files from other cloud services including Dropbox and Google Drive, which is convenient if you're switching from one, or simply want an extra backup of important files.
As with pretty much all online storage services you can share your content with friends or associates by either sending links or allowing access to folders and documents. These also feature permissions, so you can determine whether someone is capable of editing or merely viewing the file.
One nice sharing option is the Upload Link. This is a unique link that you can generate and send to a friend who wants to share a file with you. By using the link your colleague’s file will then be directly added onto your pCloud drive, avoiding hunting around for emails or the contents of your Downloads folder.
pCloud supports file versioning for an infinite amount of changes over a specified time period. Free customers can access any previous version of a document for 30 days, while paid ones have the luxury of 180 days.
One of the more specialist features on pCloud is that of a Crypto Folder, into which you can place files that you want to keep away from prying eyes, be they hackers or certain government agencies.
The contents of this folder are encrypted locally on your device, and not even pCloud employees can read it without your key.  pCloud uses 256-bit AES encryption for the files and folders, while the encryption key uses 4096-bit RSA, meaning that both are very secure.
Not all of the files and folders are encrypted automatically, but instead you drag the contents you want to remain private into a dedicated Crypto folder. This means you can have a mixture of encrypted and non-encrypted files on your drive at the same time, handy for sharing non-confidential documents with friends while also having and added level of security for others.
The Crypto folder doesn’t come as a standard feature with the storage plans, instead it’s an additional £2.65 ($3.99) p/m, but if you have need of a high security feature then it’s not a big price to pay, plus you can try it out for free thanks to the 14-day trial.
pCloud is an excellent service that's easy to use and offers a good amount of storage for free as well as very competitive rates for larger capacities. The option of Crypto folders for the security conscious is also a nice feature, especially as it doesn’t require the whole drive to be encrypted.

Microsoft OneDrive

Microsoft's OneDrive is the obvious cloud storage service for Windows users because it's built into Windows 10. However, the basic account offers only 5GB of free storage. That's enough for some people, but it used to be 15GB and you still get that with Google Drive.
There are paid-for plans, of course, and you'll get 50GB of storage for only £1.99 per month. And if you sign up for Office 365 Personal for £59.99 per year, you get 1TB of space (as well as all of the other Office 365 features. Find out more here).
OneDrive uses Microsoft’s Modern UI design. Folders and files can be created on the web, including Office and OneNote formats thanks to tight Office Online integration. Selective sync was introduced with Windows 10, meaning you don't have to have all of your OneDrive files taking up space on every laptop and PC.
There’s also a social element to the web version, as various popular social networks are available to be linked to your OneDrive account. This might not improve productivity, but it will make it easy to share files with colleagues.
In doing this you can set permissions for each user ranging from read-only to complete editing ability, even if you're using the free version (unlike Dropbox which requires Dropbox Pro).
There is also a feature that allows you to remotely access files on another PC via the OneDrive website. If privacy is a major concern then it should be noted that Microsoft reserve the right to scan your files to look for what it would deem objectionable content. This could be copyrighted material or things of an explicit nature. Apple has a similar policy, making the two potentially more intrusive than their competitors.
If you're a Windows user, it makes sense to sign up for the free 5GB account, and if you're willing to spend a little, £1.99 per month for 50GB doesn't sound too bad. But pCloud gives you ten times this amount for little more per month.

Amazon Drive

You probably didn't realise it, but a big part of Amazon's business is cloud storage. So Amazon Drive isn't merely a 'me too' service. Drive used to be much more basic than its counterparts and was only for backing up your photos and videos. But now that has changed and - if you're an Amazon Prime member - you get unlimited storage for photos and 5GB for videos, music and other files.
In addition to the basic package Amazon also includes a music storage service - Cloud Player - which entitles you to keep 250 songs online for free. These files can be accessed on your mobile device (Android and iOS) via the Amazon MP3 app, with the option to stream or download them. 
If you need more storage, then for £55 per year you can have unlimited storage. 
Apps are available for iOS and Android, plus for Windows and Mac. There's also the Prime Photos app which is - as the name suggests - dedicated to photos and backing up your phone's camera roll.
In Prime Photos, faces are recognised automatically, so you can quickly search for photos of someone in particular, or even objects. It's similar to the way in which Google Photos works.
The main Amazon Drive app has a simple, easy to use interface so you can find the files you need. Like other services, files saved to the Amazon Drive folder are backed up to the cloud automatically.
Amazon Drive used to be a confusing beast. But now that it's a full and proper backup service for all your files, and offers unlimited storage for a sensible annual price, we're happy to recommend it.


Mega is a New Zealand-based company set up by the German-born entrepreneur Kim Dotcom in 2013, who now has no involvement with it.
Mega puts its security credentials front and centre. Unlike some of its rivals, this service provides encryption in every part of the process. Anything you send to the cloud is encrypted locally, on-route, and on the destination server.
Mega itself doesn’t have any way of accessing your information, as you hold the encryption key. The upshot of all this is that anything you store on Mega is only able to be opened by you.
To achieve this there are local clients for Windows, mac OS, and Linux, plus there are also secure browser plugins for Chrome and Firefox. Apps are available for iOS, Android, Windows Phone, and even Blackberry.
The standard free package affords a whopping 50GB of space. If this isn't enough you can have 500GB (€99 per year), 2TB (€199 per year), or 4TB (€299 per year) and increased bandwidth with each package so you can share files back and forth with friends.
Sharing is easy with other members of Mega, behaving in much the same way as Google Drive and OneDrive, by allowing you to send an invitation to a friend and set the level of actions they can complete (view, edit, etc.) You can also send links to non-Mega users, but this involves also privately sending them an encryption key so they can access the files.
There are also a few secure communications features: video chat, voice calling, email and IM. These are encrypted end-to-end, making them more private than Skype or Google Hangouts.
With its generous free account, fast service, cross platform appeal, and highly secure nature, Mega is a very good choice for most people looking for an online storage solution.


There are several services that offer secure storage in the cloud, but Tresorit is definitely one of the best.
Annoyingly, the free package is somewhat obscured when you initially sign up. You get 3GB of storage space, but have to try out a free trial of the 'Premium' package which costs 10 (£8) per month. This doesn't mean you have to pay, as you can choose to revert to the Free account, but we don't like this mechanism and it stands out when compared to almost every other cloud storage service we've tested.
The Premium account itself offers 100GB of storage, versioning support for previous instances of a document, and granular controls over user permissions on the files and folders you share. There's a Solo account which costs 25 (around £21) per month and gives you 1TB of storage. 
One of the reasons that Tresorit is so secure comes down to the way files are encrypted. With a local client installed on either your Windows or mac OS machine your data is encrypted locally, then sent to the Tresorit servers where it remains encrypted. You retain the decryption keys (not that you’ll ever see them) and not even the staff at Tresorit can access your files, thanks to their Zero-Knowledge policy.
To add a further level of security you can enable two-step verification, so even if someone steals your laptop or ID, they’ll need your phone to access the data. The servers are also based in the EU and governed by Swiss privacy laws which should keep it out of the hands of any invasive national agencies that feel it is their right to purloin your personal information.
Business package customers, who pay £16 p/m for 1TB of storage, also have the ability to destroy documents remotely, ban the ability to print, copy, or email documents, and set restrictions on how much a recipient can edit a file.
Tresorit has updated its interface for version 3.0 to feel more 'native' on Windows and mac OS but there's also the web portal and mobile apps (Windows Phone, iOS, Android, and Blackberry) that look good, are simple to use, and perform reliably.
On the desktop client you can drag folders from other drives into the Tresorit app and it will encrypt and sync the files up to the cloud but leave them where they are on your machine, so you don’t have to restructure your files to fit in with Tresorit. Alternatively you can save files directly to the My Tresors folder and it will be available through any Tresorit app.
Tresorit still needs to address the cumbersome way new users reach the Free account, but if you are looking for a very secure method of storing and sharing sensitive data with colleagues and friends, then it's a very good service, especially if you sign up to the Premium or Small Business packages.


If privacy is a major concern then SpiderOak might be the cloud storage service for you. Most of the mainstream offerings all encrypt your data on their servers, but SpiderOak has a different approach.
Once you’ve set up your account and downloaded the desktop client (Windows, Mac, and Linux are available) you can transfer files to your local folder, which will then encrypt them before syncing them to SpiderOak. This might not sound that different, but it means that your data is readable only by you, as the key is local to your machine.
SpiderOak calls this ‘Zero-knowledge privacy’ as the employees at the company can’t access your data and, by extension, it should also mean any interested government parties would also find it extremely difficult.  
Traditionally this would make accessing files from numerous machines more problematic, not to mention sharing with others, but the team has worked around that. SpiderOak Hive is the control centre of your storage. This app, which runs locally, is very similar to the Dropbox folder on your desktop, although the interface has a little more detail.
This includes which of your other devices have the desktop app installed, and gives you access to the file tree within their SpiderOak Hive folders. You can also choose local files to backup via a menu, and there are helpful stats to keep you up to date with the activity on your account.
Where rivals such as Google Drive and OneDrive are tightly integrated into wider productivity suites, SpiderOak is simply there to store your files securely. This means no Office-style apps, or online collaboration with colleagues. You can easily share items and send secure links to files from the SpiderOak Hive, although this involves setting up a Share ID (free and simple) as another way to protect your data.
This obsession with security runs throughout the system, with strong warning messages appearing if you decide to let the app remained logged in all the time. Some may find this annoying, but you can override any of the warnings and it’s never a bad thing to be reminded that convenience isn’t always the bedfellow of safety.
A basic free account comes with 2GB of storage, but the snag is that it's only a 60-day trial.
SpiderOak nails its colours very clearly to the mast with its focus on security and privacy. If these are the most important elements you require then it is clearly the best choice. It may lack the sophistication and integration of some rivals, but what it does it does very well.


Sometimes mistaken for the similarly named Dropbox, Box has been around longer than its more famous counterpart, having started out in 2005. It's primarily a business service, but Box still offers personal storage options.
The free package gives you 10GB of free space. This isn’t quite as rosy as it sounds though, due to the fact that Box limits files to 250MB for free accounts.
This is markedly lower than the 10GB limits of OneDrive and Dropbox, and 5TB for Google Drive. 250MB is more than adequate for most documents and spreadsheets, even hi-res photos, but it's going to be a problem for a lot of videos.
The free account doesn’t support versioning either (being able to restore previous versions of a file).
Upgrading to the Personal Pro plan will cost you £7 per month, earning you 100GB of storage and a file size limit of 5GB, or you could switch to the Starter business plan for £3.50 per month, which also offers 100GB, a slightly lower 2GB file size, but works with teams of 3-10 people, supports document encryption, granular permissions and stores previous versions of any file.
Functionally, Box is very good. The interface in the mobile apps (available on iOS, Android, Windows, & Blackberry) is slick and well designed. There are plenty of options for creating, uploading and sorting files.
The web portal gives you the ability to create new documents in either Microsoft Office, Google Docs, or web-based formats, which you can then edit in Box via a free, downloadable plug-in. 
One of the real benefits of its enterprise background is the excellent range of apps that exist to increase Box’s versatility. There are programs that allow you to link Office directly to Box, so all files are saved there, an FTP app so you can migrate older data onto the site, and a whole host of others that are listed on the website.
There’s a lot to like about Box. The service is fast, solid, and offering 10GB of storage space certainly catches the eye. It’s just a shame that many of the best features - such as versioning - are only available to paying customers.

Knowhow Cloud

Knowhow is a service offered by UK retailer Currys PCWorld, but it's really LiveDrive rebranded. We’ve heard many good reports about the reliability of LiveDrive, so that’s a good start, as keeping your data safe is the whole point of signing up to a service such as Knowhow.
There are three storage options: 200GB, 2TB, and 4TB. However, there are other variables, such as number of devices allowed, and how many years the packages last. It’s confusing and should be simplified. The most tempting offering we found was for 2TB covering five devices and costing £30 per year.
The second element of the service is the Briefcase, which is a general online storage facility not linked to a specific PC. Here, via the web portal or your computer, you can upload and download files just as you would on Dropbox or OneDrive. These files can be accessed via your PC, phone or tablet, with apps being available for iOS, Android, and Windows Phone.
Design-wise, the interface is clean, simple to understand, and when you finish the initial install the app immediately starts a backup of your system. We’d like to see the options of which folders you want in the cloud appearing first, but it’s an easy thing to quickly rectify. Still, presumptuous software is something that never finds us overjoyed.
Security is obviously an important element in any online service. Knowhow Cloud encrypts data in transit using TLS to fend off any interceptions, and the Briefcase files are encrypted on the users machine as well. Files on the Knowhow servers are not stored in an encrypted form, but Knowhow assure us that they remain very secure behind several layers of protection and are unidentifiable to any snoopers.
The servers are all based in the UK, which in some ways is encouraging - as it keeps the NSA at bay - but of course we have our very own GCHQ to worry about. Any problems are handled by a UK-based customer support team - a pleasant surprise.
Knowhow Cloud is cleanly laid out and the backup features are genuinely useful. If you have a lot of data you want to store securely in the cloud, then it could be a good service, but for most people it seems pricey and may offer more storage than you need.


Mediafire might be a new name to many, but the Texan company has been around for nearly ten years, starting off as a file sharing service. You can still share files in much the way that you can on Google Drive, Onedrive, Dropbox and others, and can post pictures, videos, and other files directly to Facebook, Twitter, Pinterest, Tumblr,  Google+, or Blogger, from within the Mediafire portal.
The free account comes with 10GB of space, but this can quickly be expanded by various easy tasks. All in all, you can boost the free account up to a very respectable 50GB of space.
There are a few signs that the basic account is free. Files are limited to 200MB, and you’ll see ads when sharing or downloading any files from friends. There's a Pro account which costs $5 p/m  for 1TB of space, up to 20GB file sizes, and no ads.
Using Mediafire is pretty much the same as most other online storage offerings. You can create folders, upload and download files, plus (if you want it to) your mobile device will automatically backup any pictures you take.
If you install the desktop client then a new folder is created on your hard drive and you can just drag files to it like any other standard folder, except the Mediafile one will then sync automatically to the cloud drive.
There are a few nice touches in the interface. Any media files (Mediafire supports a wide range of formats) can be played in the Mediafire browser, which means you don’t have to download the file first. In practice this worked well in Chrome and Internet Explorer, but Firefox had issues playing back videos in our test.
Another smart feature in the desktop client is the ability to take a screenshot on your PC, annotate it, and then share it with friends. While this might seem a little random, it could be very useful if you’re collaborating with others on something and want to quickly show them what you’re thinking.
There are also new features on the way, with mentions of music and photo apps that will presumably have a focus on social media and sharing.
Mediafire is a solid, simple-to-use service that can be built up to a hefty 50GB of free storage if you have a few friends. It’s nothing new, or indeed special, but that’s not always a bad thing.

Apple iCloud

In 2014 iCloud Drive changed to allow you to store any document or file, even if it wasn't created in an Apple app, and access them from a PC (via iCloud for Windows or in addition to iOS and mac OS devices.
It's hardly a surprise that there's no app for Windows Phone, Android or Blackberry, though, so it's not really an option if you don't currently use an iPhone or iPad as your smartphone or tablet.
You get Keynote, Numbers and Pages folders in iCloud Drive but you can add your own. Lots of third-party apps are iCloud Drive-enabled now, and since iOS 9 there's an iCloud Drive app too. (This is sort of being replaced by the new Files app in iOS 11.)
Note that iCloud Photo Library is separate from iCloud Drive. It's quite confusing. You can find out more about the difference between them here.
The 5GB of free storage is super stingy as it's only a fraction of what you need to use the full range of iCloud services including backing up your iOS device online. You'll have to pay £0.79/$0.99 per month for 50GB, £2.49/$3.99 per month for 200GB, and £6.99/$9.99 per month for 2TB.
A recent addition to iCloud Drive is the ability to share files between apps, so you can make a chart, then put it in a presentation, for example.
iCloud Drive also means you can start work on your iPad then continue where you left off on your PC.
While iCloud is secure, much of the data is encrypted at what Apple calls ‘a minimum of 128-bit AES’, with the more standard 256-bit reserved for Keychain Passwords. Apple also reserves the right to explore the contents of your files if it have cause to believe that it contains illegal or harmful material.
iCloud Drive is starting to get some of the great collaboration features that rivals including Dropbox offer. However, it still lacks selective sync, which is a deal-breaker for some. If you're an Apple user and are willing to pay at least 79p per month for the privilege then it's well worth taking advantage of iCloud Drive, but for those using other operating systems we'd suggest looking elsewhere.


Mozy offers a very limited free service with 2GB of space and the chance to get more via referrals. Paid-for packages starting at £4.99 per month.
It's a pretty standard online storage package but allows you to select which folders from your hard disk they wish to store online, syncs automatically (once you download and install the client software), and allows you to access the files from other computers via a web portal or mobile app.
Clients are available for Windows and mac OS, while iOS and Android platforms are also supported. We spoke to Mozy about any upcoming apps for Windows Phone or Linux variants, but at the moment there are no plans to develop in those areas.
Some useful features include 30-day versioning, where all instances of a file are kept for 30 days so you can restore them to a point in time before mistakes were made or corruption might have affected them. There’s also the ability to download all of your stored files with one click, which could prove very useful if you need to move to a new computer.
Bear in mind though that there are some restrictions on the amount of hardware you can use. The lower tier packages are limited to backing up one PC, although you can access your files via the web on other machines. For a multi-computer setup you’ll need to move up to the £7.99 p/m service, which supports three PCs and gives you 125GB of storage.
The interface is nothing special, but acceptable and stable. Once the Mozy Home and the Sync clients are set up you simply click and drag folders into the Mozy drive and it will store a copy in the cloud, plus you can adjust which folders are backed up, along with several other modifiers, all with relative ease.
The mobile apps follow a similar pattern in the design stakes, with aesthetics giving way to functionality. Performance wasn’t exactly stellar though, and we’d hope that the mobile side of things would see an overhaul in the very near future, otherwise Mozy could easily find itself left behind other more optimised services.
Mozy offers two types of encryption (256-bit AES or a 448-bit Blowfish key) which perform the essential part of encrypting your files while still on your computer, rather than sending them across the internet to the servers to do the job there. The upshot of this is that it is much harder for someone to hijack your information en route to the servers and find anything they can use.
If security is your prime focus then Mozy has a lot to offer. The versioning support is good, local encryption is always our preferred method, and the one-click restore option is a nice addition.
There’s still work to be done on the design elements though, and 2GB of free storage is very small these days. Mozy seems to be intended for your most valuable data, rather than a storehouse for everything, and viewed that way it could prove a very useful tool.

Zoolz Intelligent Cloud

Zoolz is a service built with the business world in mind, but this means that Home users can access some pretty nifty features, even on the free tier.
'Intelligent Cloud' refers to the various search and storage tools available, all of which are powered by Zoolz’s AI technology.
Facial recognition is a notable example, as it can quickly locate images that include certain people. This is obviously helpful if you want to store lots of family photos, but don’t want to go through the laborious task of labeling every snap.
There are other photography based search features too, such as entering metadata details on which device a picture was taken, the option to find images that contain a dominant colour (making all those sunset shots a doddle to locate), or describing items in the image itself – say a cake or candles for all those birthday memories.   
Optical Character Recognition (OCR) also means you can find keywords in documents (including ones you’ve scanned) simply by entering the words into a search.
The service claims to offer stable streaming for any video or audio content you may have. On the free account this is limited to SD, but the 1TB £9.99 tier offers 4K or HD. You just need a fast internet connection and enough storage on your account.
Pricing is granular, with the free account offering 5GB of storage for one user that can be shared across three computers and two smartphones or tablets. This also gives you the option of backing up an external hard drive if you wish.
£2.49 per month grants you 100GB, plus an additional mobile device and multiple external hard drives.
There are two Family plans, the £5.49 per month option that has 500GB of storage which can be shared by three user accounts, using up to a maximum of nine computers and six mobile devices.
Then there’s the 1TB plan, replete with space for five users, fifteen computers, and unlimited mobile devices.
Everything runs on Amazon’s AWS platform, which is usually rock-solid, and features 256-bit AES end-to-end encryption for high levels of security.
Zoolz has loads of features, and if you’re into photography it should appeal.
The pricing offers a good range of choice, just be aware that the free tier comes with no support. For that you’ll have to pay, but we don’t think that’s unreasonable, and it you get good value for your outlay.


If you were to set up the most basic accounts on each of the services we’ve reviewed you’d have over 100GB of free online storage, and even more if you included camera uploads and friend referrals.
All are not created equal though, and there are some that stand out as the best deals. Dropbox is still a good choice thanks to the sheer number of platforms it supports. If something is going to link to a cloud provider you can bet that Dropbox is most likely the first on the list.
Google Drive and OneDrive are both excellent options if you use Chromebooks or Microsoft Office respectively, but if you want loads of free storage, then Mega is tempting thanks to its 50GB of free storage. 
Tresorit and pCloud are two services that deserve a lot of attention. Security is a very important consideration these days and both of these  manage to provide encryption in a way that doesn’t interrupt a normal workflow and is easy to manage - especially in the paid versions. 
Even if encryption isn't your top priority, do check out pCloud as it's really very good and has competitive prices for those needing lots of storage space.
Photographers, or those who just have a lot of image files they want to store and search, should take a look at Zoolz. The facial recognition feature is clever, and the pricing spread makes it easy to find something that fits your needs. 
Amazon shouldn't be overlooked, and its unlimited storage for £55 per year is good value if you have gigabytes upon gigabytes of files that need backing up.