I voted other, as I am currently using Avant Browser
This is basically a front end to IE that provides all the benefits of tabbed browsing and ad/pop-up blocking.
I was having some problems with Firefox with compatibility and performance. I configured FF with the setting provided in the other thread, but I was finding that after a while it would slow down again (not sure if this might have been a problem with the cache or something).
And because it is essentially running IE in the background, it is 100% compatible.
Very happy with it.