Here are the pros and cons of each -
SM Naruto - Insane speed, super strength, increased durability, increased chakra potency, rasenshuriken, frog katas, can sense chakras in a huge area like a village.
MS Sasuke - Weak version of Tsukuyomi, Amaterasu, Susanoo without the legendary weapons (hopefully he never gets them).
Those are just the bonuses given by their modes, I wasn't going to label all of their normal abilities.
Now for the detriments caused by each mode.
SM Naruto - Five minute intervals up to twenty minutes, unless he can pause in battle.
limits the number of clones he can make in the normal battle. Those are basically the only negatives of SM.
MS Sasuke - deteriorating vision, intense pain caused by Susanoo, bleeding eyes. No bonuses to speed and strength like Naruto has.
EDIT: Naruto in sage mode is infinitely faster than Sasuke and Sasuke was able to dodge a few Amaterasus shot at him by Itachi. So Amaterasu would only be a problem if Naruto is just standing there talking to Sasuke. The only advantage that Sasuke has is his genjutsu. The Susanoo arrows shouldn't be too much of a problem to dodge for SM Naruto. And I think Naruto's rasenshuriken might be able to tear up the Susanoo depending on which stage it is at.
Well both of u have brought up some good points. But I go with SM Naruto or draw.Ms sasuke he has a better defense, and has faster attacks he can get naruto with his arrows or amaterasu. And he also has the option of genjutsu. MS sasuke was superior until naruto got Km which changed everything around. Sm naruto isawesome but ms sasuke has the right tools to beat him and naruto greatly needed speed to counter it and now he got that with KM.
Well look, as Itachi Namikaze said, amatarasu wud not be the problem. Also Sasoonu arrows wud probably not either because he has clones, durability and probably other defense jutsu. Now as for genjutsu, it would not work as a matter of fact, Naruto cud put Sasuke in a genjutsu because of Ma and Pa. Genjutsu wud not work on Naruto because Ma and Pa can release him and also SM is immune to genjutsu, why? Because genjutsu is gone if there is an outer chakra source that disrupts it. Basically what SM is. In SM the energy of nature is coming in u, to go into SM u actually gather nature energy. The nature chakra will break the genjutsu. The only way Sasuke cud beat Naruto is if he gets him with an amatarasu or arrows but by then he wud be out of chakra himself that is why Kishi said they are equal in power. Also rasenshuriken can pierce through Sasuke's susanoo its not that powerful. So yea, its draw or SM Naruto.