I'm on the fence:
-I like the speed of Safari; it's very, very quick (slightly quicker than Chrome) but some apps don't work.
-Firefox is my normal default browser due to adblock and a good balance of speed and features, I guess I could probably set something similar up for others though.
-IE8 I'm very impressed with, it's got some long overdue features like crash recovery, and compatibility is very good. If it had come out a couple of years ago I probably never would have started using FF.
-Chrome I've basically ditched for now, it's got some really annoying updater that runs in the background (even after I uninstalled it? GTFO!), and like Safari I've hit some compatibility issues. I can't really find any reason to recommend it over Safari.
So at the moment I'm sticking with FF and hoping that it can gain some ground on the speed of Safari.