It's a hard call, but I would say that the action has always been the main draw, but only very closely rivaled by character development and story progression. I watch a lot of movies and the stunts will look too outlandish, simply because it has been recreated using safety harnesses and wires and all of these things to make it appear that someone is doing something impossible. Anime has a way of making action flow nicely, a la Samurai Champloo and Ghost in the Shell. Everything has a fluid look to it that gives me the ability to suspend disbelief and give in to the illusion. I do love the hell out of some character development, which few live action shows really give to me. I can name just as many that give me that depth of the individual as I can that I've enjoyed for action, but the action was generally what drew me in first.