I thought the title of the thread said ONE fighter of your choice.
But, I'm gonna go way out there, and say Charles "Krazy Horse" Bennett. Sure, his record is aweful, and he's a plain criminal. But, imagine the people that would get behind this guy. He's pure entertainment, and Dana Whites loves his crazy motherf*ckers. He might not be a legitimate contender for the LW title, but he'd sure put on a show with a lot of guys in UFC's current LW division, and give quite a few of them a run for their money.
Plus, I wanna see some post-fight backflips off the octagon.