Both are pretty good. Like the guy above me said, you'll never know if Korra will end up winning or losing a battle. The fights in Naruto on the other hand have some good action, some decent strategy but it does tend to get a little bit stale when the good guys do win most of the time. Obito vs Kakashi, Gai vs Madara, Hashirama vs Madara, Naruto vs Sasuke *during the kage summit*, Sakura and Chyio vs Sasori, Kakuzu and Hidan vs Kakashi and his team. They are all examples of a decent fights. So I'd say both.