This week's Versus from DC pits Batman vs John Constantine… and if you think about it, there is a lot of similarities between the characters. Batman is a human among being of immense super powers who holds his own through his intelligence, courage and equipment. Constantine is a human among beings of immense supernatural powers who holds his own through his intelligence, courage and magical artifacts. Both of them are excellent detectives and know how to get things done. Both have friends they can call on (or summon) for help and never give up. The difference in the fight might come down to Batman's stringent sense of morality versus John's more malleable one… but Constantine tends to be over confident at times and could be his own worst enemy.
I'd have to put my money on Constantine. Batman is the ultimate fighter, detective and everything else… but his experience with magic and the supernatural is limited and John's not afraid to use any trick in his arsenal.