No one has mentioned Spider Oak
https://spideroak.com/
If you have sensitive data they encrypt it and do not know the key. Dropbox encrypts your data and may or may not know the key. Google Drive does not encrypt b/c they need to see the data for optical character recognition (yeah right).
The little sensitive digitized data I have is encrypted on a usb drive. I make certain to secure delete any decrypted version after use.
I use symlinks for some files in my home directory to my Dropbox directory and in turn to my Google Drive directory (Grive in linux) and make certain none of that data is sensitive. All this stuff is worth exactly what I paid for it as someone else mentioned.