I use the IE7 beta 2 as standalone to do bugfixing and stuff. The ie7 rendering engine is a huuuuuuge improvement from 6 so I'm very happy with it.

Being an advocate of webstandards, most people think I would be a firefox user, but I always disliked firefox, I use it for development only.

I don't like firefox because;
-it uses clumsy tabbed browsing
-it renders webpages slowly
-it uses waaay more memory then other browsers

My browser of choice has always been Avant Browser, wich I like because
-it uses ie rendering engine, so I have no problems logging into my back accoung and stuff
-it's the fastest browser (it beat Opera in speed pretty recently)
-it has incredibly ergonomic tabbed browsing functionality, wich has evolved over many years
-it has many tools that you can use to streamline your browsing behaviour, such as url aliases, mouse movement commands, better favorites management, really to much stuff to name.