We are talking coolest, right?
In my opinion the coolest is Ghost Rider. He's not my favorite but he's probably the coolest.
I mean look at the bike man! The guy has the single most wicked bike in comicdom. Not to mention the costume and the look. He's got a flaming skull for a head for crying out loud. He has a chain for a weapon and....
You know what? Strike that. He's cool in a late-80's I'm a bad @#$ kind of way. To me, that rocks but nowadays. The coolest is probably someone we totally wouldn't expect. Like Nightwing. He's cool. I'll go with Nightwing.