I've been using the stock app since I got my G3 and really appreciate the pop up windows rather than it just appearing in my notification tray or taking up a whole screen. Coming from my S4 that was one of my biggest complaints - I used another messaging app that popped up bubbles like the new FB Messenger does but didn't handle group messaging well. My only complaint with the G3 was the lack of being able to preview my messages in the lock screen like I used to with my S4. Someone recommended NiLS and it worked perfect. Now my messages and other notifications show on the lock screen with a summary.
Question on Hangouts - a lot of people prefer that as a messaging app. Does it require all of your contacts to be on Hangouts as well or will it allow me to message a cell # directly?
Thanks,
-Rob