I had a friend named
Francesca who was always called
Fran. While I like
Francesca, and
Frances, and even
Francine to a degree, I don't like
Fran, and that's why I'd never use any of those names. Any nickname other than
Fran for any of those names seems so forced and artificial. I think it's a bad idea to use any name for which you don't like the most obvious nickname, no matter to what degree you intend for that nickname never to used.