I've tried others (as you can see by my site) but Copy (by Barracuda) is turning out to be the best cloud storage platform I've worked with so far.
The reason that I've begun to use this software so extensively is focused around my need to administrate multiple systems in a timely manner. This requires me to have scripts on each system that control things like firewalls, configuration scripts, service scripts, documentation and all the support files that go along with these things. For the most part, the scripts are the same and for those that are different, I can store them in a folder specific to the system.
Now, you're probably saying "yeah, yeah, but other cloud services do that too" and wondering why is this better than… say Dropbox? For starters, the SPACE! They give you 15GB to start with and if you sign-up through a referal you get an extra 5GB. Next, they're cross platform, Android, iOS, Mac, Windows, Linux (even command line!). This is a huge benefit where a lot of other services put focus into mobile devices and Windows, Copy goes the extra mile.
It handles the file syncs between the servers with a UID so that way it can keep track of what's synced up on each of the clients. From a command line you can run it as an application, sync by sync or flip it into daemon mode and run it as a full on service that syncs changes as they happen.
Either way, it is definitely worth the effort to check out this utility, you will not be disappointed!