Asami is absolutely beautiful too. But Azula for sure; First and foremost I love her hair, the bangs especially. Her eyes are really pretty in shape and in that really amber-gold color. Much like Mai, I love her head shape and complexion. She's pretty with her hair down and up--I personally like it down more. She's also pretty with and without makeup. Whilst the lipstick suits her very well, she's also a natural beauty. And then there's the fact that she still looks beautiful even when she's in the middle of a breakdown. In fact, I think she was at her prettiest during it--prior to chopping her hair off.
Both are gorgeous, the two most gorgeous Avatar women EVER, but definitely Azula. The style of The Legend of Korra is too angular for me. Azula is more natural looking because she doesn't have as much make-up on. Even without make-up she's still gorgeous. She's especially gorgeous with her hair down. She has such gorgeous red lips, stunning gold eyes, and beautiful skin. Her smile actually has two different looks to it. It can look sexy with her evil smile, but when it's a sincere smile it really lights up a room. She even looks gorgeous when she has her mental breakdown.