First off, Iron man wins this with relative ease. If you hear otherwise, they're wrong...and I'm one of the forum's biggest Spidey fans. But I'm going to request that people not be bags about it to you because you're kinda new and probably just trying to get the feel of things.
I'd suggest learning to use the search, if you haven't already. There's a bit about it in the rules thread. Because this thread (and likely most of the threads you'll think of making) have been done before. http://www.killermovies.com/forums/f77/t432545.html
Um.... first of all, I am not new, second, I know about the search, and nothing came up for this, and last, I don't think Ironman would win this with relative ease, although he would probably win it.
I meant it as a helpful suggestion, not intended to be patronizing. That's all. And you joined in March, so I consider you new. A hearty "meh" if you disagree, but again it wasn't intended as a slight.
Here's a question for the Spidey-ites:
How would Spidey; with the greatly enhanced spider-sense [as portrayed in the recent "What If"], do against Tony?
Tony wins , via long range attacks. He doesn't even have to get close. He could destroy all of Spiderman surroundings, and eventually destroy Spidey as well....