Sage Naruto. He has all of Might Guy's strengths without any of Might Guy's weaknesses. However Kishimoto doesn't understand biology. Fun fact, if you were to try kicking the air fast enough to fly, your legs would fly off your body because they are traveling at speeds faster than the speed of sound which also happen to be approximately the same speed as modern bullets. Since Guy can be injured by a Kunai traveling at 30 mph, we know that his body can't take that kind of damage.