2. Peter Dinklage - MODOK
Though MODOK did not appear as the villain in the second Captain America movie (and probably to the film's credit, given how successful it was), that wasn't for the want of trying from one writer involved on the first movie. Co-writer Christopher Markus apparently lobbied hard for the enduring villain to be considered as the follow-up to the Red Skull, particularly based on the success of Red Skull's design, and the potential for what he called a "terrifying movie with MODOK," but nobody seems to have been on his side. That the villain hasn't yet appeared is not fatal for his chances, even if some might unfairly dismiss the character as too silly for the MCU (Red Skull was met with similarly disapproving grunts), and Markus' fantasy pick for casting the character - Peter Dinklage - is easily the best suggestion for bringing the character to life. Yes, he might require something of a rethink in design, but abandoning his iconic look entirely would be a mistake, even if it would be more important to focus on the elements that have made him a recurring and popular foe for multiple Marvel characters.
Who It Definitely Shouldn't Be: Patton Oswalt. Not because he wouldn't be perfect, but because he's already been cast as Eric Koenig for Agents Of SHIELD, and because Marvel allowed Oswalt to joke about the character becoming MODOK as a self-deprecating joke - which would rob any potential development in that vein of its impact...
"When they first told me the characters name , Ill admit the first thing I did is I went on Wikipedia and looked up the M.O.D.O.K. character to see if Koenig was maybe his name before he became M.O.D.O.K., but it wasnt. They keep on talking about the Clairvoyant in the show and Im like, is that M.O.D.O.K.? Am I M.O.D.O.K.?"