Hes not in his prime yet. Prime is the point when you are at the best of your ability. Naruto only uses a few jutsu, Shadow Clones, Transformation, Sexy Jutsu, and Rasengan. He might have other variants of the Rasengan but its still stems from the basic Rasengan. He utilizes just two jutsu in battle and has much room to grow, so does Sasuke. Neither of them are prime yet.