Here's another character that I'd never heard about, before I did some hunting. When looking for some characters counterparts, I'll search the web and for Captain America in particular, people would suggest Superman, or Wonder woman, etc. But they don't really have that much in common. Then I found Commander Steel... while actually looking for info about Steel, a potential counterpart to Iron man.
It's Citizen Steel now but nice drawing
For Ironman you should do Batman, Bruce at least plays Billionaire playboy philanthropist by day. They're both geniuses and super tech savvy. They even both have British butlers, Jarvis and Alfred.
I thought about doing that, but I went with Moon Knight & Batman, as they seemed a bit more similar, at least in terms of look and feel. (Millionaire, entrepreneurs, tech savvy, fight crime at night, capes, 'Dark Knight, Moon Knight', etc etc) Although Bruce and Tony do have a lot in common as well.
Nicely done, although I would have paired the good Captain with either DC's Guardian (another shield-slinger) or with MLJ's The Shield, the Captain's predecessor among patriotic superheroes.
I was thinking you should compare lex Luther to tony, mainly because of them being rich and their battle armor