I am an avide Firefox user. That is what I use on my PC at home and my Mac at work. I use it because of the greater security offered (especially from FF2 verses IE6) but more importantly I love the extensions that you can use with Firefox. Stuff like Ubitquity which I wrote about yesterday and have been using tonnes at home and at work.
With the new version of IE 8 beta 2 out though there are some very cool features that at least entice me to try out IE 8 in the future. Probably one of the most compelling features to me is the suggested sites. Basically it suggests sites that are similar to the sites that you are on. Seems kind of like stumbleupon (which i love but kills my time). I wonder if it would help in finding some design inspiration.
Think you would view a site with cool art work and then hit suggested sites. Voila now you have other sites that have some interesting arty thing to them.
There are lots of other neat features, most of them covered in Firefox 3. The only thing that will continue to hold me back from jumping into IE 8 as my fulltime browser is the lack of my favorite extensions like Ubiquity and the web developer tool bar. If IE 8 can catch up in the extension category I would consider making the switch.