Of course at the moment I'm gonna say Kakashi.
While Naruto is vastly more powerful than his teacher, he is also too emotional. His emotions can heavily impact his decisions and he needs to learn how to reign those emotions in. Naruto has the POWER to become the Hokage, but he lacks the brain.
He isn't too young, look at Gaara. Gaara is by no means "weak", he's just been pit against extremely strong opponents. His age didn't have a bearing on his ability to protect the village. Gaara without the Shukaku is much more suitable for paperwork and can make mature decisions, as he is telling Naruto to do.
Naruto is still in the past. While I think he will succeed in bringing Sasuke back and converting him, he needs to learn to make a strong decision towards what he is going to do about Sasuke. Either kill him or let him go.
To the people who say Kakashi will die in the near future, you guys have to understand basic literature. A manga series is still a type of literature, albiet one with pictures and talk bubbles. Kakashi died, and Kishimoto used his death to help Naruto symbolize his change in his dealings with hatred, as you can see Naruto thinking about it the moment he actually meets Nagato. He came back to life as well, and that also had to have a reason. They probably did it to make him Hokage. Not only that, but Kishimoto cannot keep killing off too many people that are this close to Naruto, as they have to be there to see him become Hokage and all that other happy ending stuff that is common in anime. On top of that, what would Madaras motive be to kill Kakashi paticularly? It is true though that Kakashi could die protecting Konoha, or Naruto. What I'm saying though is that it is still to vague, but I believe that Kakashi will stay alive.