It's sad when fans compare the powers and abilities of MARVEL and DC superheroes, because all of them are on the same side and that's our side actually! Still it is unavoidable for fans to wonder how will they fair if they'd ever face off with one another. Unfortunately the movies do not definitively define their powers like the comic books do and if you're a fan of both universes, then you probably know that the elite top tier of MARVEL rivals that of the DC universe.

However, for this argument we will only consider their respective movie universes and exclude other sources of information. Based on the movie Superman is more or less equal to Hulk and Thor strength-wise, although I must admit that he is approximately 1.5 to 2 times more durable. But Thor can heal himself using the lightning and Hulk too has regenerative capabilities similar or even greater than that of Wolverine.

Iron-Man on the other hand is about 1 - 3 notches down compared to Kal-El or any of the top tier Kryptonians in the movie when it comes to strength and durability as obviously his has only been enhanced by the suit. But with a ton of exotic weapons packed in his suit he will give the Kryptonians a hard time before they can put him down. If the Avengers will fight as a team then they'll have a good chance at winning regardless who or how many they will face, even though I can see Captain America, Hawkeye and Widow dying in the process.

Hulk will be the hardest to put down and he may be the only ace that the Avengers need to win. If he can one-shot punch an alien leviathan, then any Kryptonian even Superman himself will obviously get hurt from an attack like that and let's not forget that the angrier the Hulk gets the stronger he becomes. He can get strong enough that the Kryptonians and even Superman can't handle him anymore.