I prefer "Miss" as it has much happier connotations for me ... When I was in grade school, we had this striking sub-teacher who radiated feminine power. I was in awe of her ... right up until the moment I accidently called her Mrs. She turned on me with such a harsh, ugly look and nearly shrieked, "MZZZZ! It's MZZZZ ! I'm not married anymore and Mrs. is dead!"
Now that I'm grown up and divorced, the term Ms. still makes think of that teacher. When I hear the term "Ms." her harpy voice echoes in the back of my mind, "MZZZZ!" and I shudder. It's silly, but a part of me is always a little afraid that if I identify myself as Ms. then, I too may somehow become that bitter, angry woman .... silly. I know protocol is that if you still use your married name after a divorce, then it's Ms. and if you go back to your maiden name it's Miss (or at least I assume that's he way it works) .... *shrug* I usually just have folks call me by my first name :-)