Great choices here, guys.
I'm strongly drawn to Rebecca Linares on this one, but you have to recognize Sasha Grey and Jenna Haze - super sluts. I'd have to break it out into classic, current titleholder, and up and cummers. In that last category, Anna de Ville is about as hot as anyone, right now (thanks, Ruskin_2). That Gia DiMarco pic makes my balls ache, quicky101. I know it's predictable, but I'm casting my vote for Jada, because that ass controls me.
Taken from an article entitled, "Five Reasons I'm an Anal Warrior"... I mean ... c'mon, anal fuckin' warrior! With that ASS!
http://straight.fleshbot.com/6006100/five-reasons-i-am-an-anal-warrior-by-jada-stevens