I don't know why anyone is getting upset. The descriptions for some of those were pretty funny, especially Swarm, and it looked a little tongue-in-cheek.
Before you guys make a list, maybe you should put down what the criteria are. Otherwise, you'll just have a popularity contest of Spidey vs. Wolvie. My suggestions would be:
1)Opportunity for character growth/exploration
2)Visual appeal
3)Coolness/Weirdness/Quirkiness factor (which a lot on that list depended on to be there-Swarm, MODOK)
4)Has a tag-line(It's Clobberin' Time!, Sweet Christmas!, Justice is Served!)
Using my criteria, I'll nominate Iron Fist. He has a past that I'd like to see better defined. There's something kind of oddball about his partnership with Luke Cage that I find interesting. He, hands down, has one of the coolest, if completely unrealistic, costumes in the MU. And the Iron Fist is also a cool visual. No tag line, but he's around Cage enough, so Sweet Christmas, give him a break.