5) Have Thanos Be The Main Villain
The big bad of the MCU and Marvel Comics in general is an obvious choice as a villain for multiple reasons. He’s imposing, he’s able to take on the Avengers single-handedly, he’s got strong motivations that keep him fighting and is an iconic figure that would translate well to a game. The potential boss battles, the opportunity to study his character, even the plentiful cutscenes where he can just monologue make him a completely deserving pick for the main antagonist.
There are certainly other possibilities with villains, like Galactus, Ultron and Doctor Doom, but considering that Galactus and Doom belong to Fox and Marvel just did Ultron in Age of Ultron, Thanos seems like the most logical choice. If nothing else, he’s able to appear larger than life thanks to his presence and personality without needing Godzilla-level size.
It’ll really depend on whether Marvel wants to put all of their Thanos focus in Infinity War, but if they don’t think it’ll be a case of overexposure, then they can’t go wrong with a villain of his caliber for The Avengers Project.