Like most of the responders here, I use Firefox. I recently tried out the beta for the 3.0 release. It's much better at not taking up so much system memory. But some of the plugins I use didn't work with it, so I decided to wait til it's released and the plugin developers have time to upgrade theirs.
Well I am using Opera and I think Opera is best for me since I am using it from 2005 and I have no problems with their quality and features.
My new fascination is nailed on Apple Safari. You got that feeling inside Apple's dazzling beauty. The interface of Safari speaks of grandeur and of untold elegance.
Use Firefox all time but if want to check anything related to site display review then sometimes use IE too. DON.
I use FF although I admit to being a late starter moving over from IE now I dont think I would ever change back or move to something else unless it was far superior quite happy.
I use firefox for routine browsing but it has some problems in displaying the website outlay. Hence I use IE to check my site after every upload.