I use Chrome on my desktop.
For me, firefox takes way too long to load, crashes too much, and is slower than chrome.
On my laptop, I use Opera, because its the only browser that can run flawlessly with no slowdowns on it.
Edit:
To IE users, do you at least have the sense to use IE9? As far as stability, security, and standards go, IE9 is much better than any previous incarnation...it still doesn't fare well with the other browsers, but at least its something.