I have IE8, only because I may have to use it at work at some time. After becoming familiar with it I choose Firefox.
I've used Chrome at work and it doesn't work well with custom written programs like we have there. I run IE7 for that and then run Chrome for everything else.
I think I'll try IE9 but only for a little while. I don't trust IE for anything other than work. IE8 is a piece of crap.