Batman. Why? He can take down Superman, and Supes would obliterate Spiderman.

Here's a better explanation. Batman has a mind that can cripple even the toughest of opponents. His brain is a perfect engine of ultimate fear and he is the expert in learning and manipulating the insecurities and fears of his opponents.

Peter Parker is a 20-something year old kid with severe insecurities and a massive lack of faith in himself.

Batman's battles are not waged solely with fists. The fact is, he could beat Peter Parker into complete submission with words alone. All the "spidey sense" in the universe won't save him when he starts doubting his own abilities after having 20 years of his worst fears and failures hurled into his face simultaneously. Batman is capable of defeating any human opponent, because he understands every inch of the human condition, especially in the area of it's flaws.

Peter Parker doesn't have the willpower to best the Dark Knight. It's a kid with superpowers vs. the Devil himself. No contest.