I'd go semi auto pistol. Like Glock or m&p. Because a revolver can stopped if the perp grabs and keeps the cylinder from rotating. A semi auto will still fire even if they are gripping the gun. As close as that will be to you then grabbing your gun become a real possibility.
You'll be able to fire the one round that is in the chamber but a hand wrapped around the slide and barrel portion will prevent the gun from cycling.