I use Crazy Browser (version 1.05 though!!), fast just like IE6 but with awesome tabbed browsing and pop-up blocking and a few other cool bonuses.

FF doesn't seem as efficient or as fast to me but it is definitely a fast and safe browser with hella cool add-ons/plug-ins. It has come a long way and it is hard not to like it, especially the version 2.x! I have started to use more of FF since version 2 came out but I still can not do away with IE6 engine based CrazyBrowser just yet....but I say a big NO to IE7!!

Another browser that have improved greately as well is Opera 9.x! Fast and full of nice features!