Argue until your fingers are bleeding on your keyboard. It's whomever Kishi decides wins, wins. So here we go -
Side Movie that takes place during the events of the war, totally ignoring continuity. Sasuke learns Edo Tensei, brings his brother back again and forces him to attack Naruto with him simultaneously. Clones, lightning, black flames, raining rasengan, susanoo, bijuu mode, and the fight that should be at the end is happening NOW....
A. Naruto wins, beats both of them and doesn't kill Sasuke - see exact role reversal of their first fight at the Valley of the End. Queue sad sack violin music from the anime, the audience feels like they should be learning something, Naruto leans over a defeated Sasuke and pulls a Trigun-ending and Naruto drags his ass home.
B. Sasuke and Itachi kill Naruto. Queue sad sack violin music from the anime, the audience feels like they should be learning something, the leaf is destroyed and then Sasuke opens up a small retail store in the Hidden Cloud cause he has nothing left to do.
C. Sasuke and Itachi beat Naruto. As Itachi is about to deliver killing blow, Sasuke takes the hit. Queue sad sack violin music from the anime, the audience feels like they should be learning something, Sasuke and Naruto die smiling on top of each other, brokeback style.
What makes the fight good is the anticipation of the fight, not the fight itself. What if Obito fought Naruto before he met Jiraiya, who would win? What if Trunks went back in time to Dragon Ball and fought Dr. Gero then? What if Leonardo actually cut Master Shredder with his Katanas?
The point is - they will fight when Kishi decides its time for them to fight. When they do (if they do), it won't be decided on who is more powerful. It will be decided on who Kishi wants the sad sack violin music playing for, what Kishi wants the audience trying to learn, and how Kishi is going to leave the universe of Naruto before he goes to draw baseketball manga. Whether they fought now or in 10 years at the Seinfeld reunion, power level has nothing to do with the outcome.