There aren't many shows that have been able to achieve the same universal success that Avatar: The Last Airbender has, uniting people from all different kinds of ages and demographics and allowing them to enjoy a beloved cartoon filled with action, wisdom, and much more.
While the overall story itself is still a masterpiece, one of the main reasons the show was so successful was because of the vast array of characters that the creators, Bryan Konietzko and Michael Dante DiMartino, introduced the world too (as well as their hybrid animals). And with such a large amount of amazing characters to comb through, it's only natural that you might have a favorite.
Honorable Mention: The Masters
The skills that Team Avatar developed over the seasons weren't inherent - they needed to be learned through teaching. So, as Aang and the gang prepared to face-off against Ozai, it only made sense that they had people who helped give them the knowledge they'd need in order to do it.
If Bumi, Pakku, Piandao, or Jeong Jeong are your favorite characters, perhaps you're a person who is accustomed to teaching rather than doing - but make no mistake, even as a mentor you're more than capable of keeping up with your students.
Mai & Ty Lee
Mai and Ty Lee certainly proved that they weren't inherently evil when they finally chose to turn on Azula, but that shouldn't take away from how absolutely bad-ass these two ladies were. Living in a benders world (but not benders themselves) Mai and Ty Lee could take on anybody who was stupid enough to underestimate them.
With Mai and Ty Lee as your favorite, it's possible you're a person who can be manipulated by psychopathic friends, however there's also a slight chance that you're being manipulated because said friends know how strong you can truly be on your own.
Appa & Momo
Appa and Momo were the beloved pets/companions that were the only remnants of Aang's past/culture. Not only could the sky-bison and winged-lemur fly around as easily as Aang could, but they were both incredibly intelligent and could communicate (to an extent) with the people around them.
With Appa and Momo as your favorite characters, there's a slight chance that you've got a soft-side for animals and loved how these two conveyed so much without saying a single word.
Iroh
Everybody needs an Iroh in life. Despite growing up in the fire nation and being set to become the next Fire Lord, Iroh lost his son in battle and immediately altered his path in order to become a more spiritual, enlightened person, passing all of his lessons on to his nephew Zuko in the process.
If Iroh is your favorite character, it's possible you've had a rough-past that doesn't necessarily reflect who you truly are underneath it all. You also probably appreciate life-lessons, wisdom, and having long discussions with people you care about over a cup of tea.
Azula
Azula was as cunning as she was clever, arguably sitting upon the throne as the most sadistic character in the show. Despite being a firebending prodigy, Azula was labeled a monster by nearly everybody around her and eventually ended up going insane from a lust for power.
If Azula is your favorite character, perhaps you're a person who focuses too much on achieving goals at any cost, even if it means betraying or hurting your own friends/family in the process.
Suki
Despite only appearing in a handful of episodes, Suki quickly made her presence felt on the show as the leader of the Kyoshi Warriors and eventually became an official member of Team Avatar (not to mention how she and Sokka started dating as well).
If Suki is your favorite character, perhaps you're a person who can appreciate good things in moderation and focus on the things you do get rather than the things that you don't. However, you're also always available to partake in an adventure and help your friends when they're in need of it.
Sokka
Due to his lack of bending, Sokka was often underestimated during his time on the series - at least, by everyone not on Team Avatar. As a result, Sokka was often targeted as the weakest member but would always come through in the clutch and save everyone (either with a brilliant idea or with his trusty boomerang).
With Sokka as your favorite character, you might be a person who doesn't exactly stand out from the crowd right away and it takes a few clever words and funny jokes in order to get people to appreciate your worth.
Toph
Even being a late addition to Team Avatar, Toph was arguably the most popular character in the entire series. Her brass attitude combined with her exceptional earthbending skills allowed her to be incredibly blunt with anybody that underestimated her (which was almost everyone since she was blind).
If Toph is your favorite character, perhaps you're a person who truly understands/relates to the phrase "a cover is not the book," very much appreciating how powerful/self-sufficient Toph was despite seeming like she had a disability.
Zuko
Zuko was a character who arguably had an even more complicated past than his uncle, spending nearly the entirety of the series grappling with what his destiny was and how he should achieve it. Luckily, he ultimately chose good and joined Team Avatar, forever cementing his place in fans' hearts.
With Zuko as your favorite character, maybe you're a person who understands how truly difficult it is to try and redeem yourself from past wrongs, and perhaps you're a person who also had to go on a rough journey to achieve your own redemption (just as Zuko did).
Katara
Katara was a character who truly proved that greatness can arise from anywhere. Starting the series as the sole waterbender of the Southern Water Tribe, Katara trained herself into becoming one of the greatest waterbending masters in the entire world, eventually ending the series by defeating Azula, a lifelong prodigy.
If Katara is your favorite character to watch, you could be a person who understands that hard work and discipline are the greatest traits to possess when attempting to obtain your goals. You may also be a person who appreciates training/learning over raw-talent.
Aang
The world's only hope was a twelve-year-old kid who couldn't have been goofier if he tried. Raised by monks, Aang had many distinct qualities such as being a vegetarian and a pacifist, only ever fighting out of defense and even refusing to kill a maniacal overlord.
With Aang as your favorite character, there's a chance that you're more kind-hearted in nature than those around you and that you're always trying to put out fires rather than start them. However, despite your attempts to make everybody agree at all times, you're fully capable of putting your foot down when enough is enough.