The cloud-storage widget that's right for you depends, of course, on your cloud-storage service of choice. Google's Drive storage service, which has a valuable home-screen widget, integrates nicely with Android, so if you don't already have a horse in the race, you might want to check it out.
Dropbox and Box, two more popular online storage services, also offer Android apps with widgets. Some of the options offer more features, but all of them make it simpler and faster to access your cloud and upload files from your Android device.
Download Google Drive, Dropbox and Box for free on Google Play.