REASONS FOR AANG:
1: Aang lost his entire people to the Fire Nation and spent most of his life in an iceberg. This tragedy makes him a compassionate person.
2: Ended the 100 Year War.
3: Defeated Fire Lord Ozai.
4: Defeated the Dai Li (after the 100 Year War).
5: One of the Founders of Republic City.
6: When alive, was in a wonderful relationship with the world's greatest healer, Katara.
9: On his journey as the Avatar, Aang and his friends saved villages throughout the Earth Kingdom.
10: Aang later restores Korra's bending.
REASONS FOR KORRA:
1: Korra lost her bending. This tragedy causes Korra to become a compassionate person. Very soon after, Aang restores her bending.
2: First person to ever tame a Polar Bear Dog.
4: Korra was an awesome pro-bender and entertained the people of Republic City.
5: Is a in wonderful relationship with a hot firebender, Mako.