I have used Dropbox since they launched. Never heard of the other one.
DB is quite useful, personally and professionally. Yes, I am aware of all the issues with DB in the news of late. Am I concerned? Personally, not terribly so.
I use DB to share/remotely access/sync non-confidential, low importance stuff anyway. It is horrible about the breeches and they need to clean up their house internally, but I ain't too worried and will give them the opportunity to set things aright.
The service and benefits are useful enough for me at this point to take this stance. Plus I have 4GB of free storage, a couple above and beyond the 2GB standard [from simply filling out a few non-personal surveys online and from references.]