I was always taught "no one." Mrs Grunden, Miss Stahlman, Miss Ramsey, Mrs. Mackenbach, Mrs. Bauer, Mrs. Sunderman, Miss Duffy, Mz. Drummond (ah, the lovely Mz Ruta Drummond!), Mr. Long. Mrs. Buchanon, "Prof" Kohler and Mr. Howard can't all be wrong. Not to mention our own catmama.
jools:
Personally I prefer no-one or no one
I don't play favorites either.