The most dynamic performer I have ever seen live is Prince. I feel that he's what should be the measuring stick for what a musician/artist should strive to be...daunting task, I know. If you only know about Prince based on his eccentric ways and media scrutiny, well your eyes have not yet been opened.
Charisma and talent are the main ones. Some people who have almost no talent but also have a lot of charisma and very interesting to watch and listen. What I also love is for them to be beautiful on the inside, I do not care if someone has a lot of talent and charisma, if they also are dirtbags then I am not a fan!