Ok Guys, I would like to help us here. First, you might have noticed that I like to defend Naruto and sometime the Senju/Uzumaki in general. This is not because I love them more than the Uchiha. Rather, it is because I think they have been given a very difficult role by Kishi. You can summarize their role in to the following, and not forget this when comparing the two group in general.
In all decisive Naruto/Hashirama vs. Sasuke/Madara fight, Naruto/Hashirama is always trying to retrieve Sasuke/Madara while the later is going all out to defeat them.
So this is the dilemma in this manga. From this logic, it is easy from the outcome of the battle that Naruto/Hashirama is much stronger than Sasuke/Madara. I used this logic to predict that HAsihirama was a god before Madara on Mangahelepers.com and most people insulted me. The thread was created before the late flashback, and you know the outcome. Now, let dig into Naruto vs Sasuke, and prove why Naruto is stronger than Sasuke.
1. Naruto's goals are much bigger than Sasuke's
I am pretty sure you understand what I mean. Naruto wants to be Hokage, and now has also taken Jiraya's quest for peace in the shinobi world. Sasuke's goal is only to avenge the Uchiha, which is a goal solely restricted to Konoha. If you add to these facts Naruto being the main character, it is easy to see that Naruto will be much stronger than Sasuke. Besides, needless to notice the large pool of his chakra+Kyuubi's. Note that in the shinobi world chakra is like fuel, and once you own it, you become king. Right now, if you add Naruto's late chakra control, he can basically perform all non KKG Jutsu.
2. Back to childhood
Most people who like to oppose the fact that Naruto is stronger and even very smart in battle always dig their argument out of his childhood. However, there is another interpretation of Naruto's childhood vs Sasuke's childhood. This interpretation is very crucial to understanding why Naruto is stronger than Sasuke in particular, and why a gifted Senju end up being stronger than an equivalently gifted Uchiha.
As a kid, Naruto lack coaching, and was only interested in being acknowledge by others. In class, he only showed his prankster side, pretending that he doesn't care about being shinobi. The reason was that when he become serious, he noticed that everyone leave him alone, and felt more pain. On the other end, at home, he was a very hard-worker, but without parent to guide him - resulting into failure. He had no one to tell him that he was failing because Kyuubi's chakra was mixed with his, and make his chakra difficult to control. Thus, Naruto was thinking that he failed because he is not smart. This is also what the bad user will think as well.
On the contrary, Sasuke had the potential of a genius clan. He was trained by his father, and could observe his gifted brother. Clearly, it is easy to see the gap between the two world. While regular student knew only bushin and chakra basis, a typical Uchiha kid was doing something else - trying to unlock the Sharingan. We even learned later that Sasuke went on mission with Itachi.
From these, I think comparing the childhood of the two guys is not accurate. One of them was a shinobi while the other was someone who was trying to become a shinobi in secret while hurting in public.
Well, as an advocate of Naruto, I want you to understand that Naruto's goal as this point was to be acknowledge as human, not as a shinobi. Sasuke's goal was to be acknowledge by his father as an Uchiha (rings Sharingan and fire Jutsu).
3. Graduation and post graduation period
After failing the exam, Naruto got an additional awakening. You all know what happened. His body finally responded to his mind, and he got his Kage bushin. In all my interpretations, I always tell people that Naruto unlocked his Uzumaki KKG. The reason is that in the same way Sharingan (eyes) is the Uchiha KKG, life force and body feat are KKG of Uzumaki/Senju. Og course, similar to Uchiha, not all Senju can unlock it. So far, we have seen Hashirama, Naruto, and Nagato (perhaps Kushina and Mito).
From this point, you all know how Naruto caught up with base Sasuke up to the Sasuke leaving the village. This prove that once a Senju become a Shinobi, and start to fight for people he loves, he becomes really stronger quickly. Even, in Naruto's case, Kishi was forced to prevent him from having a lot of Jutsu to keep a balance between him a Sasuke. Kishi was even forced to give Sasuke the CS to balance also for Kyuubi cloak one tail.
4. At VOTE
Recall what I said earlier. Naruto was fighting to save Sasuke from Orochimaru while Sasuke was hesitating between killing him to get MS or not. You can see that actually, at the end, Naruto noticed that even if he wrecked Sasuke and took him back to the village, Sasuke will not stay happy. So Naruto changed his initial decision into marking Sasuke mentally. If you recall, even at the hospital roof, Sasuke always said that Naruto will never be able to put a scratch on his forehead protector. At the end of the VOTE battle, Naruto chose to tell Sasuke that he can while Sasuke tried to killed him. Even with the CS2 Chidori on Naruto's heart, Naruto regenerated before Kakashi came.
It is up to anyone to chose the winner of this fight. As far as I am concerned, I think Naruto won the fight, and could have terminated Sasuke if he wanted. He went down not because Sasuke was stronger. Rather, it was because he chose to save Sasuke rather than killing him.
5. SM Naruto vs MS Sasuke after MS Sasuke vs Danzou.
Some people interpreted Naruto's words literally when he said that he is still weaker than Sasuke. The problem is that they still forget that Naruto's intent is not to kill Sasuke, but to save him. What kind of power will someone need to stop an MS Sasuke without killing him. Well, I think it is a godly power. Naruto needs to be twice or thrice stronger than Sasuke so that the overwhelming power can make Sasuke give up. This is how I interpret Naruto's words.
Interestingly, Sasuke also said that he need Itachi's power to crush Naruto. So he seems that Sasuke could not crush Naruto. Actually, if you dig into it, you will notice that my interpretation is not bad. The reason is that Sasuke was already blind while Naruto has Kyuubi and SM. Clearly, we can even say that Naruto was not talking about Sasuke alone. At this point, Naruto was talking about Sasuke, Zetsu and Obito because Sasuke alone was a blind Uchiha.
I think I could elaborate, but it is a pain because I know that most fans don't care about analyzing the plot. For example, some people said that Naruto beat Pain because Pain did not want to kill him. However, Nagato last shot during their meeting was said to be the strongest. Nagato said that Naruto couldn't free himself from his control at this range, but Naruto did it. He freed himself. This prove that he could have freed himself when he was locked down before Hinata.
Well, I think anyone can think what he wants, but Kishi has made the different route clear for Sasuke and Naruto. The only way Sasuke has a chance to being on par with Naruto is to become a world-level villain. This is because Naruto will become a world-level hero very soon.
