Chrome with AdBlock and Xmarks. It feels much faster than Safari. I do wish they would update the Chrome UI so that I could have the 50px or so additional vertical resolution in Safari, but the performance trade-off is worthwhile.
Chrome is awesome sauce poured on top of awesome pie I love not caring about any maintenance of the browser (updates automatically, bookmarks, passwords, plugins, themes synced around any computer I sign in on) and some quality chrome webapps such as Springpad make Chrome irreplacable. The performance is way better than either safari or firefox too.