I love hawkeye and ultron, both don't get enough live from the community
Quicksilver and Hawkeye
Not really my favorite. But two underappreciated characters that I can think of are. Pepper Potts. In Iron Man she risked her life twice to help Tony and she saved Tony in the third Iron Man. Also Howard Stark because he built Caps shield and he gave Iron Man the knowledge to create a new element to power his suit.
Hulk
Bucky Barnes
hawkeye