All of the villains could have been could if done well, but I think Sasuke, Madara, Obito, and Kaguya were not written properly, especially the latter two, since the first two actually had very apparent potential that fell flat, though that's not to say Obito and Kaguya didn't have potential to be good villains. Overall, only Orochimaru, "Tobi", and Nagato were good villains.