I am currently using Firefox, I went through a spell with Google Chrome and a few years ago Internet Explorer (ugh). From my experiences Firefox is by far the best browser all round, although I am meaning to try Safari, I have been told the speed it exceptional.
Yeah I think Safari renders the best.
Firefox because of useful addons, and because I ride a firefox bandwagon.
I personally as a longtime Firefox fan currently use
Flock.
It's based on Firefox 3.0.1 and makes all my feeds quickly accessible thus keeping me up to date on everything I need to know.
Opera, Haven't upgraded to 10 though, I'm happy with 9.5 I hate FF there's just something about it... I think Opera is faster on my machine anyways.
Google chrome. It's not cluttered, no ugly buttons to look at, and I just have to type 1 letter to get to most the websites I visit, quickly.
Go omni Opera all the way... But I do have Firefox on a couple of my computers.
My favorite is Firefox for it's addons.
DownloadHelper for youtube vids or 'other' video sites + AdBlock Plus
Firefox, although Opera is quite good, I just like the addons. Google Chrome was quite fast for me too.