Well a while ago i would've said naruto loses badly but in the last year and even the last chapter Naruto's power has jumped to far greater levels.
Current Naruto vs Classic Ironman (or any other you think is better excluding extremis [no other gadgets or items except his armor])
No prep involved, no battlefield restrictions, whole world could be used, and it's unpopulated, Well i suppose it could be a mix between naruto world and marvel world. kyubi can be used but he has no control in this battle.
If it's thought that one character still has a huge advantage over the other then we can change the op.