First thing's first, a point on how I've chosen the services for comparison. The services featured are the biggest players in the consumer cloud storage market. It should be noted that there are some other worthy cloud storage services, but this approach means that most people may already have an account for one or more of the services featured.Platforms
The first consideration is on what platform each of the offerings are available. As you'd expect, all provide software that can be installed on Windows and Mac computers to allow for easy upload and syncing of files to the cloud. Apple is the most restrictive, however, and does not offer an Android application for iCloud, unlike its competitors.
Amazon's Cloud Drive has an app for Kindle and Microsoft has a OneDrive app for Xbox, both of which may be useful for users in those niches, but are unlikely to be deal-breakers for most people.