I agree that their power levels are pretty much equal. Going into the War Arc, Naruto obviously had a huge advantage over Sasuke. However, the So6P essentially evened them out.
That said, Naruto and Sasuke have other advantages in this fight other than just power levels.
1. Naruto - Naruto has essentially been fighting different versions of Sasuke since the original Sasuke Retrieval Arc. Plus, his move set and abilities are kind of catered to defeating Sasuke. Naruto originally fought Sasuke, and since then, he's faced an Itachi clone, Obito, Pain, Itachi, Nagato, Obito again, Madara, and Kaguya. These characters all sported abilities that are similar, if not more powerful versions, of Sasuke's current abilities. Naruto is also perfectly suited to face a genjutsu user, and his primary techniques (the Rasengan and Shadow Clone) cannot be copied or is so universally known that it really isn't worth copying. Comparatively, Sasuke only knows about his abilities by observing other Sharingan/Rinnegan users. Sasuke may not even know what the Rinnegan is fully capable of doing. He never saw Nagato in action, and thus far, has only used Chibaku Tensei (which he saw Madara use earlier).
2. Sasuke - He's essentially been sitting out the majority of the War Arc, and even after joining the battle, has taken a back seat to Naruto. Comparatively, Naruto has been awake, expending huge amounts of chakra for days. Prior to the War, Naruto was training with Bee. Then he fought Ay and then tangled with pretty much every enemy on every battlefield. In other words, Naruto has fought this war essentially single-handed. Therefore, Sasuke should have a huge energy advantage over Naruto, even if Naruto has more experience with his own abilities and in fighting opponents like Sasuke.
