I'm using firefox with chrome theme.
(in my opinion)
I like chrome on my old pc, it really fast, and it has the best debug tool I ever used for js and css.
But when I bought a new pc,
I use ff instead, because there is almost no delay between ff and chrome when I start them,
so compare with chrome , I like ff's addon adblock plus. and other powerful addon,
but chrome's debug tool is better!! (Firebug is good too, but it's not as easy as chrome's)
i have Firefox(with Chrome theme), Chrome on my pc, errr almost forget, IE 7 is here too.