Well you're making a big assumption that Orochimaru is good again just because he is with sasuke and gang..for all we know he could end up being the final villain of Naruto series. After he came back, he even mentioned that he still want's Sasuke's body. Right now he is a wild card, and because of all the stuff he did in the past I would put him higher than Obito in terms of being a better villain. Obito might even turn good and help SA after his battle with Kakashi.
Also, Nagato shouldn't even be on the list..he turned good in the end and saved the lives of hundred of Leaf Ninja. Plus he genuinely wants peace, whereas Oro just wants power/immortality.
So I don't agree with your list.