In one of the issues that makes up the digest "Spider-Man & Human Torch: I'm With Stupid," Reed Richards tells Johnny Storm that Peter Parker had tested as being as intelligent as Reed had been at Parker's age. That Spidey hasn't gotten his PhD yet or achieved much scientifically speaks more to his difficult life than lack of intelligence. Also, Dr. Curt Connors belongs on the list if Dr. Bruce Banner belongs on the list. And didn't Dr. Hank Pym invent the android that became Ultron? Being super-intelligent doesn't mean being infallible. Finally: Is this list restricted to the living? Dr. Bill Foster (Goliath), for example....
The definates I know are 1 - Reed Richards 2 - Dr Doon 3 - Hank Pym 4 -Tony Stark 5 -Peter Parker 6 - Bruce Banner 7 - Hank McCoy The problem with Pete is that he doesn't have the resources that Reed, Tony, and the Hanks have. If he did, I bet he'd be right up there no problem. I mean, he invented his webbing at age 15. And there are other good people like Doc Ock, Conners, Radioactive Man, and so on but they are more specialized. Also, as stated, Conners couldn't cure himself, he's not on the list.
Depends on how they are applying their genius I think. Certainly, Captain America and Cyclops are the smartest tacticans in the MU. Let's not forget about Forge either. His mutant ability may be to create anything by instinct, but he nevertheless has learned what he is doing.
Going by Overpower CCG game stats (anyone else remember this game?), Richards, Doom and Sinster all have the highest intelligence rating (8), along with Dracula, and a couple more I can't remember right now. Also, has the Leader ever met Doom? Part of the Leader's abilites is thatt he can control anyone whose of lower intelligence than him just by touching them. I just think it would make for a really awesome scene if the Leader touched Doom, only to be horrified that he couldn't control him.
The WWH prologue that just came out mentions that Cho might be the 7th smartest person on the planet. Cap, yes. Cyclops, no. Cyclops is a good tactician, but he's not even the best one in the X-Men. Storm has proven to be all around better than him. I refer back to Storm beating his ass without her powers. And she didn't really do much in the way of actual fighting either. She was able to outmaneuver him, and get him into a position where she could remove his visor. Rendering him blind.