Great to see nobody has voted for that last option yet I mostly use Firefox, heck I'm using it right now. Not supposed to have it installed at work but the boss doesn't mind and I only use IE when I have to (going through works proxy )
This, although I'm not sure which version I'm using (I know it's on of the ones listed though). I've used IE since I first started going on the internet so I guess I'm just used to it.