Tango loves for me to scratch behind his ears. He'll nuzzle my hand, trying to get his head under it and when he does, if I don't immediately start moving my fingers and doing the ear rub thing, he'll rub his head first one way and then the other against my hand, to get me to start.
Jazz on the other hand loves for me to stroke her back, starting at her head and going all the way down to her tail. She doesn't mind me doing her ears the way I do Tango's, but she MUCH prefers the back stroke. She'll even sometimes arch her back, much like a cat does, as my hand's traveling down. She also likes to be rubbed and tickled under her chin, whereas Tango will jerk his head away if I try and do that, and re-position his head UNDER my hand to get behind his hears scratched. .