Here is an archive of all the past top five lists I've done over the years.
With Captain America: Civil War due out later this year, I was inspired to do a Top Five Captain America/Iron Man fights.
Avengers Volume 1 #4
So Captain America has just woken up in the future, realizing that his life has passed him behind AND his partner, Bucky, has been killed in front of him right before he dies. Then, after he processes all that information super quickly, he then has a bunch of costumed folks doubting that he is really who he says he is. So what does he? Dares them to "conquer him."
How badass is Captain America? Anyhow, this Stan Lee, Jack Kirby and George Roussos fight is not really a full fight, but damned if it isn't awesome none the less.
Civil War: Casualties of War #1
In this one-shot by Christos Gage, Jeremy Haun and Mark Morales, Cap and Iron Man call a truce during Civil War to talk. They end up fighting, of course, but interestingly enough, they do it sans armor for Iron Man, as Gage cleverly intercuts their fight with flashbacks to the time (during Bob Layton and David Michelinie's run) when Cap trained Tony Stark (who he didn't know was Iron man at the time) how to fight...
I love the flashbacks, but the fight itself just sort of tapered off out of nowhere.
Avengers Volume 5 #29
During the Original Sin crossover, Captain America discovered that Iron Man and the Illuminati had wiped Cap's mind of their existence. He was none too pleased about this and he confronts Tony in his workshop along with the rest of the Avengers...
Very cool sequence by Jonathan Hickman, Leinil Yu and Gerry Alanguilan, but it got cut off a bit too quickly by the Time Gem going haywire to rank higher.
Civil War #7
This Mark Millar, Steve McNiven and Dexter Vines sequence is the heart of the Civil War storyline, but it's really more of a Captain America AND Vision vs. Iron Man fight, right?
Otherwise, it'd be in the Top Five for sure!
Captain American Annual #9
In this story by Roy and Dann Thomas, Jim Valentino and Sam De La Rosa, all the inhabitants of a small town in Washington have been driven crazy by infected trout (they're celebrating their annual trout festival). So has Iron Man, leaving Captain America to try to figure out a way to stop his teammate (Cap has determined that extreme cold kills the virus, so he lures Iron Man out to the top of a snowy mountain to try to freeze the virus out of him, and hopefully hold him off until the cold works)...