the FF work together the best out of the 3. sue is mighty powerful and a force to be reckoned with. i know they are out numbered and dont have as many "advantages" as the other 2, but they are the most resoursful, talented and efficient out of the 3. they have the best defence and the best track record as well.
you must also take into consideration that although the hulk is on the avengers at this point, he has battled thor and iron man already, he has joined the team only to avoid confrontation with the authority, the next issue he quits, and not too much later he takes on the entire team. i dont recall him rejoining ever sence though he often confronts them in battle so you cannot rely on him using all of his strength being for the cause of the side of the Avengers. no FF member would ever do anything like that when a threat like the X-Men and the Avengers are there.
Hulk thinks for himself and himself only, and with hotheads like Tony and Thor along side him it is more than likely the Avengers will fail for their team is still incomplete. my point is that this team only lasted for an issue and a half and really havent overcome anything together. also putting the hulk on any team is probably not a good idea.
and as for the the x-men line up being "lame," like WAF said, it's the one that started it all. and they have a very good chance. jean and iceman alone are a great team. but with angel's flight, skills, and magic sword, beast's intelligence, powers, and abilities, and cyclops's leadership and powers they are hardly a "lame team" at all.
If we're going on all originals with original powers then proabably Avengers. Original Invisible Girl wasn't really that much of a force to be reckoned with was she? Neither was original Marvel Girl, the Prof used to make her do the most retarded tasks in the beginning. Iceman was just a fuzzball of snow. Warren can fly. So can Thor, Ironman, Wasp and they have other powers too.