I know it's probably cheating since it is technically an American-made cartoon, but I consider it an anime not solely for animation style, but of the great essence it has that makes it an anime: a flowing story, tremendous creativity, energy from great voice actors, great subtle messages, and overall, in my opinion, the best show that Nickelodeon has ever released on television ever.

A hundred years passed and it appears victory for world conquering for the Fire Nation is inevitable. Our story begins with two siblings from the Southern Water Tribe named Sokka and Katara who discover the new Avatar trapped in an iceberg with his pet flying bison. This Avatar is a 12-year-old airbender named Aang, who's been trapped in the ice for a hundred years and without any knowledge of a war happening and the fact that since an airbender was next to become Avatar, his people were all killed by the Fire Nation. Together, this trio takes off to the Northern Water Tribe to begin Aang's journey to master all four elements and save the world from its imbalance, while facing threats of capture from the Fire Nations especially by the exiled prince, Zuko, who is seeking to regain honor from his father.

Every single character on this show no matter their significance, if any at all, is unique and memorable. I probably could go on forever with Aang, Katara, Sokka, Zuko, the list just goes on.
Something I kinda do appreciate about the series is that it has continuity and no matter how seemingly pointless an episode may be, it does serve purpose to a series whether it's character development or we see the same place or characters again in a later episode.
What else can I say about this series? It's just fantastic, the live-action movie adaptation sucks, and I'll do a separate review on Legend of Korra