I've used Firefox in the past.
Been using Chrome for a year.
I prefer Chrome because it saves all the websites I bookmarked under my google account and preferences/saved passwords.
If I ever got a new mac, install Chrome and all my bookmarks/passwords/preferences are automatically transferred.
You do realize Firefox has the same thing right? 😉
One thing that bothers me with Firefox is it doesn't display the Quicktime videos correctly like Safari and Chrome do.