Superman is an overpowered boy scout, I'm rooting for the villains most of the time.
Robin (any one of them) is an unnecessary and bothersome addition to the Batman series, he manages to ruin the grim feeling of Batman, which is something that I and many others go to escape the comic book worlds that are either stupidly cheery, or Warhammer40K clones with so much evil that you actually may start laughing.
Iron Man annoys me, rich boy gets hurt and decides to become a superhero, a little too close to Bruce Wayne in my book (read: my book, not your's, I really don't care about trolls who start up with 'Batman is not Bruce Wayne...' stop foaming at the mouth and cool your jets). For that reason, I love the Mandarin, despite a questionable ethnic portrayal.