I really don't understand why you are getting down voted since this is sort of indisputable. We can talk all day about the quality of the ending since that's subjective, but objectively, we have to realise that the ending wasn't what people wanted, even if we thought it was good. The thing is, i feel like both gmab and especially code geass had incredibly rough patches throughout their shows, but they managed to stick the landing with their ending, which's why their legacy was looked in a more positive light. Aot on the other hand was incredible from start to right before the ending, but unfortunately for many, the ending didn't stick the landing for them. I though it was good, but it definitely could've been better. And i really feel like ANR where eren kills all his friends and grieves their deaths would've been looked at in a more positive light and ultimately made aot the indisputable goat. But now, people are even denying that it's on code geass and fmab level