I wish Avatar: The RolePlaying Game used something other than the Powered by the Apocalypse engine, though to be honest, I am not sure what. PbtA just didn't do it for me. I am not a big fan of class based systems, and to me, that's essentially what playbooks are. The balance mechanism was interesting, but the playbooks just felt way too contrived and constraining for me. It didn't help that none of their archetypes appealed to me, which is a shame, because I love Avatar-verse.
I think the bending powers would have been modeled interestingly through the Ars Magica magic system (probably still the best magic system I have seen so far in a game). No game engine truly does martial arts well, at least to the point of detail that I would like. The closest is the Hero System which has a nice build-your-own-martial-arts system. It's also quite crunchy to my liking. And you can build pretty much whatever magical system you like. My main beef with the system is the Action Phase system, and the min-maxing abuse (eg, always only buying a score of 13 or 18, because it's just as good mechanically as a 15 or 20). Also, good luck trying to get anyone into the Hero System nowadays.
I think the bending powers would have been modeled interestingly through the Ars Magica magic system (probably still the best magic system I have seen so far in a game). No game engine truly does martial arts well, at least to the point of detail that I would like. The closest is the Hero System which has a nice build-your-own-martial-arts system. It's also quite crunchy to my liking. And you can build pretty much whatever magical system you like. My main beef with the system is the Action Phase system, and the min-maxing abuse (eg, always only buying a score of 13 or 18, because it's just as good mechanically as a 15 or 20). Also, good luck trying to get anyone into the Hero System nowadays.