Im gonna call the justice league on this one if youre going to say whos going to win in a straight up fight. The best player on the avengers is either Iron man or Thor (cause lets face it, you tell captain america to hurt someone like superman who is ACTUAL US personified [an immigrant who made their life and actually achieved the dream of success and love and all that jazz, while having the boy scout morals Captain is so famous for], and hes just going to roll over and die), and they have to then fight Superman, Batman (who will go toe to toe with tony and i would say win, because hes caught more training and skill), Martian man hunter, green lantern, and wonderwoman.
and really, when the weakest link in your chain can theorectically summon and control Cthulu, whos stronger.