I can’t lie Zaheer was the best villain that has ever come out of Avatar unique motivations and the manipulation along with his ragtag team of other compelling villains creates such beautifully choreographed fight scenes and introduced the other Beifong sister. Every character had a good arc and the best progressions of character for characters like Lin Suyin Bolin Jinora and Tenzin. I think the reason why people generally don’t think of Legend of Korra too highly is because most people expect Korra too be exactly the same as Aang and because Korra severed the connection between the past and future avatars after her. But the finale sets up for Korras journey of self discovery and learning to heal from her past.

TLDR: S3 had a unique villain w some of the best character progression while giving us insight on characters pasts while also having some of the best fight scenes in the show