For me, the fact that Microsoft worked directly with the FBI to integrate OneDrive into PRISM makes the whole product something I would never touch, so it's great to see alternatives picking up the slack.
All the major cloud vendors are surveillance collaborators.
... and I have to ask: do they have any choice? Can you say no to the national security state? If I were in charge of a company with employees who have families and fiscal responsibilities, I can't say that I could. I'm sure any request from those quarters comes with an implied "we wouldn't want anything bad to happen to your company, now would we?"
The only way I can imagine a company saying no is if it were privately held and the largest investors were on board, and most of these companies are public. Being public makes you subject to all kinds of "soft power."
I hope Microsoft and Dropbox both improve their security, but Dropbox has a history of lying to customers when it comes to the security of its products, e.g. http://www.wired.com/2011/05/dropbox-ftc/
http://cryptome.org/2014/11/ms-onedrive-nsa-prism.htm