The 'Korra is a villain' notion is
slightly
accurate in that Korra is basically Zuko who had the good fortune of being born on the good guy's side. She is a flawed protagonist, and if you give her a chance, eventually she'll move you. Zuko, Sokka, Iroh, etc are some of my favorite characters in popular fiction, but Korra manages to beat them all for the crown of favorite character across both series. Korra's arc actually helped me recognize and come to terms with depression in my own life; I can count on one hand the number of times a fictional character has gotten through to me to such a degree.
Simple questions deserve long-winded answers that no one will bother to read.