My vote goes to Tox too as I can run a client on Windows, OS X, Linux, Android and even Sailfish! Just copy over your .config/tox folder or make any number of burner profiles. The fact it is encrypted & decentralized is a huge deal.

EDIT: not that video chats are high on my list, I prefer texting & audio only calls

[ Edited by NicePics13 19.05.2015 - 15:22 ]