Source: Sheddit
Makes sense for Aang to airbend far more than the others. Who's fought an airbender in the last hundred years? Plus, it's his native element that he's already mastered. He has far less experience with the others.
It's pretty interesting, given the above, that Korra is much more balanced in her use of bending. She's been practicing the first three forms since she was a child and mastered airbending during the course of the show. The writers seem to have put some thought into how both characters would fight given their respective backgrounds.
