Well,
Naruto is actually pretty powerful without Kurama, Its just he usually relies too much on the nine tails chakra now that he is able to use it. Imagine if he could use all that same chakra without ninetails, I mean he would probably only acheive Sage mode. To control all nine tails, naruto would completely change into Kurama but with his own conscience, But the physical part of Kurama is still missing. That is the only key to Naruto actually using the Nine Tails.
Sasuke would probably be a little challenge, But its all up to Naruto's strength and chakra without Ninetails.So Sasuke wins...But only cause of his circumstances right now., If he didnt have any special ability other than his own bloodline ability, it would be even.
