My vote right now would be Ohno. He's got that slimy / sinister heel persona down extremely well.
And, is it just me or does anyone else think Richie Steamboat will fall flat when he's called up? I cant see him making much noise in the big leagues. Would probably have to bring him in as a spoiled brat heel with his dad escorting him to the ring to get a strong fan reaction. If he was brought up in his current persona, I just cant see him doing much, regardless of name value.