Characters I would like to see in the game:
Red Hood (one of my favorite comic book characters)
Lobo (he is simply too cool)
Apollo & Midnighter (would be a great addition, I think)
Black Adam (because he is a badass?)
Parasite (I think he is a cool character and also easy to pull off)
Stages I would like to see in the game:
Arkham Asylum (with prisoners running around and maybe dropping stage-interactive-objects after a while)
Centennial Park (with the Superman statue ... I would like it to be crowded and as colorful as the Afrika Stage in SSF4: AE)
Watchtower (too iconic to let it out and there could be a lot of stuff to use as stage-interactions)
Ace Chemicals (maybe with poison-barrel-stage-interactives, which inflict damage over time, if the opponent hits you with them)