I use Firefox with a couple of tweaks to get it up to speed. I'm probably going to stay with Firefox and tweak the next version the same way. That way, I'll be getting seizures at how quickly I can load pages.
I have Firefox 2, Firefox 3, IE7 & Opera installed, but I usually use Firefox 3 - I prefer 2 with the extensions it's got, but it seems to sometimes not load pages right for me.
I tried safari for two days and after that my eyes went blurry for a day. All of the text is so bloody blurry! Its hard to look at and hurts your eyes, along with the silly fonts it defaults everything to.
I use firefox now, I used to use Opera but FF suits me better and is quicker for me.
if that's "blurry", never go use a Mac. Although I prefer the "blurry" text, because it looks so much better and easier to read, and keeps the proper font look, rather than "MUST.. FIT.. INTO..GRID!"