Of the TNA guys, I have high hopes for Wolfe and Dinero if they're ever given much time to actually cut promos. Both have very interesting characters and, Dinero in particular, ooze charisma.
Current guys who I think go close in the WWE are Punk (their best character, in my eyes), Cena, Orton, and Christian.
My top five:
1. The Rock: Leagues ahead of the rest. Just awesome.
2. Chris Jericho: Especially as a heel, but he could work both ways.
3. Stone Cold Steve Austin: Only as a babyface. Tremendous ability to fire a crowd up. Managed to make 'What' a quote.
4. Kurt Angle: Surprised he's been left off so many lists. In the WWE, he was hot.
5. Shawn Michaels: Can make you believe even the stupidest storyline means the world to him.