I *only* have C3, but I do confess that I'm considering going back for C2.
The primary reason is the addons mentioned above, there are several I could really do with, but they aren't on C3, and the authors are not converting them. For that I have no work around. I actually want to write business apps not games, so I need some web page hookins.
I like C3, but the browsers tend to crash from time to time, eating my work with them I've had the best luck with Chrome, and the worst with Safari. (I'm on Mac).
C2 would be a struggle as I'll have to run it in a PC window on Parallels on the Mac, but it does work.
If just doing games, C3 will get the job done, but I feel it is behind C2, and I'd be happier to feel it was moving in front.