There are literally a tons of options. I regularly use,
Dropbox,
Cubby
4Sync
SkyDrive
for different purposes
I discontinued use of SugarSync. Somehow it managed to mess up my computer and it never worked at my hand as well as Dropbox.
Box.net, I have 50GB of space but their syncing feature is pathetic. All I want to do is sync my pdf articles between mt laptop and tablet. It can't even do this job well. So this guy is off too.
Google Drive, good for my limited requirement but I have not given too much of thought as the other options are just working well. And my policy is, if it ain't broken, don't fix it.
If you are worried about any of your data, it should not go in the cloud, as simple as that.