Super hero vs super hero who becomes the champ

[TheRookie311]

I was reading a thread on spiderman vs batman the other day, can't remember if it was here or not, but the generally most thought batman would lose.

I really couldn't see that happening so I gave a big explanation why batman would win etc.

(The point) What is everyones opinion on other matchups, maybe ones that have or haven't happened and how would it go down.