Well, i'm doing this quest thingy, so this is my first blog. I have recently come to think that Batman is a much popular character than Iron Man because some comicbook readers might be kinda angry at things (people, events), show some squizoid conducts, and are not overtly social. So Batman justifies them for being as they are. While Iron Man is also a genius millionaire, but is the playboy they wouldn't dare to be. So they can picture themselves as Batman: dark, cold, serious, bitter, mysterious, etc; and as such, this character is much popular. It's a classic case of adopting an antisocial role model: if someone fails or sense that will fail adopting a positive one, then that person will instead adopt a negative one. 
 
Not that Iron Man is the best role model, with the drinking and all, but his personality is not as negative as Batman's. In the sense of being obssesed with revenge, and his violent actions. 
 
Of course, not that a person identifies itself completely with a character; that would be straight out pathologic. My point is that for the average comicbook reader, some of Batman's charactersitics, conducts and motivations are easier to identify with, compared to Iron Man.