1) Tony Stark is the most likely character to joke during serious situations, but hopefully he doesn't have the "role" of being the "comedic relief." I hope every character has a sense of humor that makes sense for the character much like the MCU. Part of what makes the movies so successful is the fact that they make all of the characters somewhat funny in their own ways and as the situation warrants; be it making light of what's happening, being sarcastic, overly blunt, or just having a funny reaction; like making a confused face. This kind of behavior makes the characters more genuine and believable because real people are funny, whether it might be inside jokes, funny nicknames or just a quick remark that points out how frustrating or awkward the current scenario may be. Even physical comedy like when Hulk punched Thor in the first Avengers or excuses like when Thor said Loki was adopted.

2) Double team moves. It already looks like you can probably combine special moves, which is amazing, but I believe it would be a bit of a missed opportunity if there aren't quick double team moves such as launching an enemy in the air so that a teammate can catch, slam and/or knock them down. I would love to be able to set up an enemy so that my teammate can finish them and vice-versa. Maybe your teamwork affinity can even be an upgradable skill which unlocks new double team moves unique to particular teammate combinations. We haven't really seen any team gamplay yet so I'll just it at that for now, since I'm sure there are some surprises for us.

3) New storylines/paths for new characters. I know this would be extremely difficult from a development standpoint, but if I want to be Daredevil for the whole game I wouldn't want him to automatically be replaced by Iron Man whenever there is a cutscene or even worse, not be able to pick who I want for too much of the game. I understand some missions need certain people for the main storyline, while other heroes just wouldn't present during a particular scenario. So maybe after I finish that scenario I should be able to have an option to do the mission the other character was in at that time; Or maybe those characters can accompany me on those particular missions. Though I admit that I would still want my character to have different lines that pertain to what is happening and is true to that character, which may make the needed mission character have different responses. Other wise it might seem like a canned script. Paying attention to details like this would give the game so much replayabilty that I personally would finish the game with EVERY SINGLE character just to hear what they have to say. I'll probably try that anyway because this game already looks so dope, but I would definitely enjoy it a hundred times more, and I'm sure I'm not the only one.

4) Eventhough I love the fact that Thor can still fight without Mjolnir, he seemed to be doing the same 3 hit combo over and over. I really hope that isn't the case when the game releases. The fact that he had so many awesome moves with the hammer actually made this stand out even more and, I have to admit, makes me have a frightening question on whether Captain America is the same way.

5) A counter system. Not like Batman where it pretty much finishes people off on its own; instead more like Shadow of Mordor/War where it stuns them or knocks them down so that you can finish the enemy yourself. This mostly pertains to Captain America, Black Widow, and any other new characters that use skills rather then armor or powers that help them withstand/defend against damage. But even so, it would still be useful as Hulk if you happen to be fighting someone like Abomination, which we know is in the game.

6) Vehicles. Eventhough I would love to be able to parkour through the city with Cap or Widow (which I also hope is in the game) if this game has a huge open world, it would be nice to have the option to ride Cap's bike or even fly the quinjet seeing as there already seems to be flying controls because of Iron Man. Maybe for people who aren't known for having vehicles they could get picked up by the quinjet and while you're in it you are the pilot until you jump back out where then you swtitch back to who you were originally. Now I know you can probably just make some kinda fast travel system that uses the quinjet, but I believe to much fast travel can make getting around too easy and boring and would take away from the joy of exploration.