Chicks like healers usually. At least from my experience that's what they seem to play most.
I've known almost a dozen female MMO players. Over half were healers. None were tanks. They don't seem to like tanking.
Edit: I take that back. I knew one with a tank alt in Lineage 2, but my point stands. Tanks are not a popular class for female gamers.
It is true, most gamer girls I have gamed with do indeed like being healers and they like playing range dps. They also like being tanks as long as they are not really tanking. In other words, they play tanks to help with any fighting impairness they may have whether fighting is not their thing or they want to take a few extra hits. Some may find Commando and Mercenaries (hyrbrid) cool too in which they can do both like a LOTRO Captain.