I have been using explorer for years.. I just recently made the switch to firefox and like it so far.
I would have to say my new favorite browser is Google Chrome, You can download it at the link below, http://www.google.com/chrome
Ever browser is having the unique functionality, Opera is famous one regarding the Java support, Firefox is famous for its Adons, Chrome is famous for the fast browsing speed, Internet Explorer is famous one due to the monopoly and java support.
As far as I am concerned I think Google Chrome is the best. it's fast and has extensions which you can use to customize it. It is also more secure than IE
Firefox annoys me with its auto updates - but at the moment it's faster. Chrome is getting there - won't be long until it takes over. baby