DropBox is pushy and needy and I've deleted an account for the third and final time.
Please, do not use DropBox.
Cozy Cloud is an open source alternative that just got out of beta and looks very promising! Clients for every platform, 5GB of free storage, the data is stored in France, but you can also run your own server at home. I've been using it for a few weeks, works like a charm - only thing I miss from Dropbox is file versioning. https://cozy.io/