It's Cavendish.
Classics don't measure sprinter prowess, sprint stages in the grand Tours do. In the history of the Tour de France, by far the most important GT and hence presumably with the greatest level of competition, no-one has come remotely close to dominating like Cavendish has. Check the record books, hardly any sprinters have won more than a couple of sprint stages in a TdF more than once.
Then take a look at the distance he puts into his rivals, when Cipollini won four in a row, two were by less than a wheel and one was on a DQ. When Cavendish won six last year, the other sprinters were struggling to stay in camera shot.