Shikamaru is Naruto's best friend.
One of the strongest bonds that should be focused on is between Naruto and Shikamaru. Not Sasuke. Shikamaru is Naruto's best friend out of all the characters in the series and I will explain why. Unfortunately Naruto is too blind by his ambition to save Sasuke to see what a great friend he has in front of him. Of all the characters, they can relate the most.
Both Naruto and Shikamaru lost their mentors, who meant a lot to them, and were taught many great things by their sensei's. When Jiraiya was killed, Shikamaru asked Naruto to walk with him. He tells Naruto that he can relate with him because he lost his sensei like himself.
We see Shikamaru's maturity and his response to Asuma's death. In the previous panel Shikamaru tells Naruto he will never get anywhere in his life if he keeps dicking around. In the current panel Shikamaru tells him he's not in the position to do that anymore. Shikamaru's advice and comfort towards Naruto just proves what a good friend he is. Shikamaru's maturity and similar life experiences is what makes those two click as great friends compared to Sasuke. Both of them were looked at as weak in the beginning. Both of them had hidden potential that needed pushes along the way to become what they are today.
We see that Shikamaru has Naruto's back and is willing to help him. What other character has offered Naruto help without it being required to work with him? Exactly.
It's a damn shame the friendship between these two isn't focused much. Naruto needs to open up his eyes and look at what he has in the village. In my opinion, his relationship with everyone in the village is more important than the bond he has with Sasuke. Other people have acknowledged Naruto. Sometimes you just can't save a person and have to accept it. Naruto has people who care a lot about him