Ive done loads of working and playing around with Cloud Storage and they all offer similar but different features depending on what you are trying to achieve. There are 2 main types System and Hardrive Back up and File Back Up, Sharing etc, the latter is what your after.
The Main Leaders for File Back Ups are OneDrive, Dropbox and Google Drive, OneDrive comes free with Windows (5Gb space) which can be upgraded up to 1TB of space either on its own with monthly subscription or gets bundled into newer Office Suits, both Dropbox and Google Drive can be upgraded by monthly subscription.
OneDrive offers a simple back up for Photos, Documents etc, and a simple sharing across Devices but starts to become painfully horrid to use when you start trying to sync different Files or Folders of your choice at any one time and its Web Only Interface is painfully slow, Google and Dropbox are similar in different respects.
If your looking at a free (10 to 20gb) or paid subscription (500mb to 2TB) I would highly recommend pCloud, it just works and is fast as its its Web access, and is more of a case of what it doesn't do in terms of features. You can download its PC App for simple Files and Folder Syncing and or you can use the Mapped Network Drive App, so the entire Cloud Storage appears as another Hard drive on your PC, you can Back Up your OneDrive, Dropbox, Google Drive into the pCloud storage so all your Clouds appear in the pCloud account, Remote Upload ie, Upload large files from a URL directly so you dont have to download a File and then upload to again to pCloud, Image and Video Conversations in the Cloud, ie upload a 1080p Video and then chose to download 720p or 480p for Mobile, it has a built in Office Viewer, Encryption etc, the feature list is endless.
https://www.pcloud.com/