FF4 beta, though I'll switch back over to Pale Moon when it catches up to FF4. Only thing I don't like about 4 is that they moved the damn refresh, home, and stop buttons to the right side of the browser. Not used to it after years of it being on the left lol.
I liked Chrome when it first came out, but I've always had stupid issues with it on several computers. I tried to try it again recently on my new laptop and it doesn't even install. Black box just pops up part of the way through and sits there indefinitely.
I doubt I'll ever use another browser unless I have to (someone else's computer, that sort of thing) unless they get add-on support on the level of FF. There's too many exclusive add-ons I use on a daily basis.