Chrome is certainly my favorite right now.
I ditched firefox a while back, after I noticed that flash videos started stuttering if I was using over a certain amount of memory. Given my excessive use of tabs, this was all the time. I fell in love with Chrome pretty quick. The UI design is pretty awesome, and gives me more screen space on my tiny netbook screen. I also really like that tabs are in separate processes, so crashing one doesn't crash the entire browser. The unified search bar up at the top has also really sped up my searching on different engines, once I had tweaked it to my liking. And the right-click->view element function is also really useful.