Ooohhhh... this is SO difficult to answer, because when I see/hear/think of MJ, I think of his voice, his moves, his short films, his style, his curls, his house, his animals, his Ehh Ohhh's, his EVERYTHING.
I might be wrong on this, but I think we can't simply take ONE aspect of MJ to be THE one thing that appealed to us. In my case, I became aware of MJ with the making of "Thriller" and I was 6 or 7 by then. And I say that I "became awared" of him, because ever since I can remember, now I know he was there, but as a little child of 2 or 3 I wasn's aware that the little boy of the Jackson 5 cartoons was the same boy singing "Ben" and the same young man singing "Thriller"
"Thriller", the video, was my welcome ticket to MJ's world. And what is Thriller? Just "a song" (his singing)? Just a choreography (his dance)? Just a movie (his short videos)? Thriller is all that and much, much more. We WANTED to dance like him. We WANTED to be the girl walking by him. We WANTED to be rescued by him.
And then "WE are the world" came out... and we wanted to follow the efforts of that young gentle sould. So he was not only beutiful, graceful, full of talent, a great dancer and a great singer... he was also a caring soul!
But maybe I was too small to fully understand that. Then came BAD. And it was a shock. If we wanted to dance Thriller before, some like me decided we could NEVER dance "Bad" the way Mike did... so... I just watched, amazed and full of admiration to him. All the videos from the BAd album are master pieces. But "Smooth Criminal"... that is a classic.
MJ is not only a singer, not only a dancer, not only a generous man. He is THE man and he is UNIQUE. I love him for his ALL. And yes, he made lots of mistakes. Many mistakes and he suffered for those; that's why I love him the most. With all his gifts, MJ was just a man, a human being just like you and me.
I love MJ. All of him!
(ok... I am a passionate fan!)