Superman = Cap
Batman = Iron Man
Wonder Woman = Thor
That's how I always looked at the Trinity from each side. It's not 1:1 - Supes is far more powerful than Cap, Bats and Tony are different in just about as many ways as they are similar, etc. - but as far what each character represents on their respective team, I think it shakes out like that.
This makes a lot of sense.
Sodlier/Hero/Leader- Superman/Cap
Playboy/philanthropist/Billionare/super intelligent/alternate identity crime fighter - Batman/Ironman
Fantasy style/warrior - Wonder Women/Thor
Of course they are very different too, but they have similarities that link them.