Girls? Which kind of personality would you like most in a guy?

Well, my boyfriend is somewhat ambiverted, but he's closer to intorverter. He's EXTREMELY private; even his closest friends don't know a lot about him. He's very reserved and it takes forever to get him to open up. It took me months. But we do have a big group of friends, and we usually hang out with at least 6 other people if we aren't alone. When we're with this group he is a little more outspoken and easy going, but not with strangers.