I use FF and have for a quite some time - lots of great add-ons and features. I dabbled with Chrome, and it's a great minimalistic browser, but I just didn't like it. I would download both, try them for a while and then make your choice on which one sits more comfortably with you.
I use opera mini for my PDA, but I haven't bothered using it for my main PC in nearly 6 years. I really didn't like it then and I'm not sure it would bring anything worthwhile to my normal usage.