Re: fire fox
Konqueror uses KHTML or optionally Webkit. KHTML was forked by Apple and eventually led to Webkit which is used in their Safari browser on OSX as well as Google Chrome's (Chromium) and many others.
Gnome's Epiphany is another Webkit browser but is not really fully functional yet.
Or you could go retro elinks?
Opera tend to do interesting things with their user interface, but I tend to find it's not supported enough on the web to be used exclusively as a browser.