There is no Google Drive linux client yet =/. What about the others? I use Dropbox on Windows, Linux, Mac, Android and I have even used it on a personal server. I have not seen anything that can replace it.

Insync works great as a Linux client/integration for Google Drive: https://www.insynchq.com/linux

Which of these use client side encryption?

There's always https://mega.co.nz/

Wuala.com does aswell (not mentioned in parent). They are a Swiss company and don't have a lot of traction in the US.

Spideroak does. Their GUI is really awful, but the commandline python script seems to work well.

SpiderOak claims to.

Why are you trusting any of them to do that anyway. Ecryptfs is your friend.

also, aerofs is pretty damn awesome. Just started using it the other week.