avengers, for sure. even though i dont like captain american. first off, ironman (definitely can beat batman). Secondly Thor (even though I dont consider him a super hero >_> [hes a pre-existing god]) will come out on top almost every time. He loses his hammet, bam¡ reach for it and it comes back to him. Third, can you say the Hulk?! Is there anything that can even beat the Hulk¿ No.
You must be more specific with discussions like this. Are we confined to just the comics, or are the movies acceptable? What about all of the animated series? If everything is included, Avengers would come out on top. If we're looking at just the comics, Justice League would be victorious.