Spider-man has already had great games. If it seems like they've hit a slump it's only because they've gone through most good ideas and are being a bit rushed now.
Superman's been deserving a good game for a while now but most only remember the N64 game. --- The flame of courage, the light of wisdom, the strength of justice, the guardians of life. This is what a Ranger is...
Iron Man could really do with a decent game. The popularity of the character has shot through the roof thanks to Robert Downey Jrs portrayal so a good Iron Man game has the potential to do really well.
The character is really easy to work with for a videogame as well. Compared to some characters like Superman, Captain america or Thor which have slightly more tricky powers to work around, with Iron Man you've got all the typical things like flying, shooting, big robots, customization, etc.
All the pieces and potential are there, I'm amazed no one's stepped up (and even more amazed that segas movie tie-ins were so awful, even by tie-in standards). --- PSN: GamingGuru1992 (UK gamer)