When editing webpages here I have to take into account that 27% of our visitors do not use Internet Explorer. The chief competitor is Firefox (20%), a choice that puzzles me as having used it I am less than impressed. It had one chief advantage over Explorer, tabbed browsing and the correct display of .png graphics. Other benefits touted seemed, to me, to be exagerrated or untrue.
I have been using Internet Explorer 7 beta for a month now and am very happy with it, it has tabbed browsing and has fixed the png problem.
Security has seen some major improvements, anti phishing, pop up blocker etc.
There have also been many other improvements so that now I see no use for Firefox et al.
Essential reading: Firefox Myths
IE 7 Tour & Download
So, what browser do you prefer?