This is kind of silly question I think. Many 4chaners, forumers, Wapanese, net-otakus talks about so called 'masterpieces' in anime, or probably talks about 'perfect 10 out of 10 score' animation. Then, what is that definition of masterpiece or perfection for you? I find a lot of people saying something like 'it was good, but far from perfect', or 'it was good, but definitely not masterpiece'. How much better it has to be in order to meet that standard of 'perfection'?
Personally, I think those are all just shits. To be honest, the only animation that I think that is absolutely perfect + masterpiece is Nausika and Mononoke-hime. Both were animation wise, direction wise, story wise, philosophy wise, character wise, perfect, imo. However, even those two might have its own flaws. I don't get how people use those kind of logics.
(***Bakemonogatari is masterpiece in my heart. )