Naturally the majority of respondents slavishly proclaimed that Batman would win because he has his utility belt and that means that he's prepared for anything and blah, blah, blah, he punched Superman in the face, blah, blah, blah, totally could kick everyone elses asses in the DC universe, blah, blah, blah.
That was a company conceit and not a realistic result of the contest.
Look, Batman's villains are only on the small scale. They fight over Gotham and on the rare occasion that Batman steps out of his city they organize quasi-nation spanning conspiracies that don't even come up on Superman's radar. Compare him to the Red Skull who literally tries to burn the world (and may have succeeded on multiple occasions depending on which continuity you follow) and the Joker doesn't even rate.