Rooney and Ronaldo. Hard to compare the two. Rooney always seemed to be a kind of football "tank", powerful and hard to stop once he gains momentum. Watching Rooney draws you into admiring the unadorned precision of his technique and his burning desire to come out on top (sometimes making him seem overbearing).
Ronaldo seems like the opposite of Rooney, seeming to possess a "lighter" touch and more finesse. While it would be ard to argue that he does not want to get the ball and score goals he never seems to be as forceful a personality as Rooney (or is he just more disciplined?). Personally, I prefer to watch Rooney's style of play.
As a casual watcher of Man U games though, the man I enjoy most watching plying his trade is Louis Saha who to me me seems to just quietly take care of business with minimal fanfare or drama.