Mmmm. I like this post because I am a big fan of words. I would say there are 2 big favorite categories:
1) Words of humiliation- I love to hear what a "stupid cunt" I am, or a "garbage pail", basically name the degrading phrase, and I love it.
2) Words of praise- I also adore to hear Master tell me I am a "good girl" or a "good pet" or that I have pleased Him. Words like these tend to always bring a large grin to my face.
Favorite thing to say to Him?
Probably saying the same type of humiliating things about myself back to Him to please Him.