Well, unfortunately there is no ultimate solution, at least not for me.
Safari is nicely integrated with the system and pretty fast, but that's about it, i miss some advanced features and expandability.
Firefox has a ton of expansions (can't live without AdBlock, Firebug and others) and great customizability (like removing close buttons i always hit from tabs), but is slower than others. FF3 is looking good though.
Camino is somewhere in between these two, last time i remember using it i quit because i couldn't close tabs with middle click and I also can't figure why they don't work on one browser with firefox developers.
Opera is lightning fast and also quite stable, but has a terrible terrible interface, I also miss some expansions.