Smile [Q] What is your fav messaging app and why

There has been so much discussion on messaging apps these days. And many of my friends use different messaging apps. Since Messaging app is one of the most frequently used apps, and I was wondering what messaging apps the group uses here and why.

I personally use Hangouts and WeChat mostly (and Line to a lesser extent). The reasons are:

Hangouts: cross-platform messaging syncing/messaging, I can use Hangouts on PC, Mac and phone.
WeChat: communicate with friends in Asia
Line: VoIP call...(pretty good quality actually)

How about you guys?