I used to use IE, but then I switched over to Firefox about a year ago and I haven't looked back.
IE had problems running on E. So, one day, I tried Firefox and I haven't see any reason to change back. It's the fastest for me and the most user friendly out of all of them. I've kind of wanted to try Chrome, but I have heard some bad things about it, so I won't tempt it.
I have no problems with IE and still use it for certain applications at work, but Firefox is my home now.