Doyle - depends on the game, but I think Emperor's on the right track. He plays a lot tighter nowadays than he used to.
Negreanu - he calls his style smallball. Whether he's loose-passive or loose-aggressive depends on the game from what I've seen of his play on TV.
Harrington - definitely a nit.
Hansen - loose-aggressive. He was kinda the poster boy for the style until guys like Durrrr came along.
Ferguson - tight-aggressive. I wouldn't say he's as nitty as someone like Harrington, but he's not getting out of line too often.