Iron man is a second tier superhero, but you have one clear thing in reverse. Superman has notoriously been known for having the worst and lame of villains. There is Lex Luthor and NOTHING else. He is notoriously too super powered ultimate being to have any interesting story or drama, and his villains have allways sucked. On the contrary, Batman has the best villains (and Batman is the best superhero character), and then Spiderman comes after him with several marvel villains (the Marvel superheroes mainly share their villains).
I know you are speaking in terms of the movies, and havent read some comics like me, but its comical you are saying Superman has the best villains, when he is the butt of the joke in having no story at all and no good villains whatsoever (He is popular and interesting ONLY because of his god like ultimate powers that give the ideal escapism effect on people. Otherwise his story is cliche as heck and has no interesting villains except ONE human one. I like despite all that, but lets be real).
Btw, you are really reaching it too much with the Iron Man plot to find things to criticise. Besides the movie, I dont like Iron Man or paid any attention to him (as a reader of comics), but the terrorists didnt have super human weapons nor were superterrorists. They were just an Al Qaida-esque elite rogue guerilla warriors who STOLE weapons in raids or as we saw in the movie, got it from Obie, the man who is the chairman of the worlds biggiest arms corp.
And I like Superman, but you mean to say Superman flying around the earth fast to turn back time or carrying a WHOLE isle made of Kryptonite that is SUPPOSES to kill him (this moment was a dark stain in the cinema history, a tiny piece is supposes o be lethal, but he carries a whole isle of it....), is less fake then Tony Stark THE genius engineer and scientist of his time building a clunky clumsy armour suit, when the terrorists already had provided him with all the equipment and material he needed? Seriously?
Differentiate you liking Superman more for obvious reasons, to finding empty reasons to criticise. The premises for Iron man was quite realistic and through to our times mostly (Billionaire celebrity arms dealer kidnapped by terrorists, they give him material and time to build stuff, and he is smart enough to build whatever he likes, so he builds a bulletproof armour, wow so shocking). Hardly fake or that much suspense of belief.