Whats the most stable version today?

Today, being the 5th of October 2015, what’s the most stable version (branch) of Asterisk:
1.8, 11, or 13? and is “Certified” more stable - they don’t seem to mention the words “more stable” only that its been tested in a Digium labs. (so what - any of this tested in the real world)

I’m not looking at this from a features or compatibility perspective… purely stability… no segfaults, no deadlocks… everything just works.

I´ll go for the Certified version and the LTS branch. Now if you need pjsip go for 13 if you dont need Pjsip go for 11.