When you're on your PC for minimum 9 hours a day, you sure as hell want a browser that you enjoy using and that doesn't crap out for no reason. Firefox is that browser. I have been using Gecko browsers for years from Mozilla 1.0-> Phoenix,->Firebird -> Firefox. I absolutely love it. I have all the extensions I could ever need and a few more to boot. (Aggreg8 of course too). The toolbar customization means that I have everything at my fingertips, from XHTML validation to javascript debugging. I have a super theme installed. A bookmark Sync extension to sync my home and work bookmarks. Firefox does crash evry now and then but that's acceptable as I never have less than 15 tabs open and constant feverish browsing and keyboard shortcuts being performed at all times. If you spend a ludicrous of time in your browser and you want to stay sane get Firefox.

I'll link to the extensions mentioned when I get home.