Dave.
Martin SHOULD get the nod but while I'd say his peak and Dave's are more comparable, Martin's was much shorter lived.
Martin > Chappelle's Show > Chris Rock show.
And Rock knows what time it is, he's brilliant but he recognizes that he's not the most inherently funny person or talented comic.
He's funny enough and smart enough to set up the jokes while also saying some real shyt. Prime example of that would be Bill Hicks, who I love listening to, yet he doesn't make me laugh that much, I kinda see Rock in that same light to a lesser extent.