MS Sasuke wins decisively. The thing about Sasuke and Naruto is that Naruto will always be more powerful, while Sasuke will always be more versatile/well-rounded. If they were both blades, Naruto would be a machete and Sasuke would be a swiss army knife. So any argument that says "Naruto is stronger than Sasuke" has to go in depth. You can't pull the A>B>C argument, because that's BS.
That said, Naruto's durability doesn't mean much against Enton for the simple fact that we've already seen it's not half as durable as Fukusaku made it out to be. SM Jiraiya's arm was taken off by an attack less deadly than Amaterasu. Naruto was pierced in the stomach by a wheelchair spike. Kabuto's SM snakes were snapped like dry twigs by Susanoo. Kawazu Kumite is almost completely useless aswell as the range increase is neglegable. When Naruto hit Hungry Ghost in the face with his frog fu his face was practically in his armpit before it took effect.
Sasuke however can lay traps on the ground (Kagutsuchi), paralyze Naruto with Genjutsu as easily as he did Killerbee, tank anything in Naruto's repertiore outside of FRS (and he may even be able to survive that with an Amaterasu shield, since the flames would devoure the wind).
And the biggest reason SM Naruto will never beat MS Sasuke? Time limit. Naruto can either stay in Sage Mode for 5 minutes, or until he uses two FRS. After that he's got to gather natural energy again, and he becomes exhausted aswell, making him an easier target to hit.