I am using Aurora 7.0a2 which is Mozilla's new Firefox browser I guess. It's pretty chill. I like the tabs
Customizing this thing is really easy too and I love it.
I hate IE personally. It is too slow and doesn't have a lot of capabilities.
I use Opera sometimes when I need to log into my website as two different users. (:
I used to use Chrome but I just don't anymore.
Firefox/Aurora is the best I believe.