Romney's rap was aggressive and as soon as he came out of the gate, he was ripping Obama a new one. Obama's was more passive aggressive which fits his personality when tackling issues.
But my favorite one of all time is Mr. T v. Mr. Rogers. Mr. T absolutely stomped him!
"So before you come to battle with your PBS crap, how 'bout I call up CPS about them kids on your lap, fool?!"
Kills me every time.