If you haven't seen funnyfox, you defintely should check it out. Pretty humorous. Personally I've been a Firefox user since it was called Phoenix. It's my default browser on my all my computers. I really like Opera sometimes too. It's great for quickly looking up documentation, like the exact syntax of Preferences for example. It's just a lot faster than Firefox (or IE for that matter.) Firefox works a lot better for Google-related sites, like Blogger and Google Maps. Opera used to really suck on GMail, too. Of course that's as much Google's fault as it is Opera's, but that's not reason enough to not use Google Maps for example.
The traction that Firefox has gained is really pretty remarkable. I've been able to "switch" my wife's parents and her sister. They were all eager to be rid of pop-ups and spyware. Firefox is really great for most people with pretty basic browser needs. It's also great for "power" users, with its myriad of extensions. Personally I use the user agent switcher and the Google bar. I'm also thinking of adding on one of the enhanced ad blockers for my home computer. I've noticed more and more sites with ads (pop-ups/flash mostly) that seem to get by the standard pop-up blockers of Firefox, IE, and Opera. That will probably only get worse for awhile.