It's kind of hard to call Azula "crazy" imo. He childhood was formed by her father and her environment, she was pressured into being perfect. Also, Azula tends to take the less harsh paths, like instead of killing all the Kyoshi Warriors and not killing everyone in Ba Sing Se. On the other hand, Light was a normal person. He was a talented prodigy at school, all the girls liked him, ect. When he got hands on the death note (a thing that can kill anyone if you have their name and face) he CHOSE to kill all those people. By the end of the series, Light probably killed 100 plus people.