I would choose
Louis;
Francis has always seemed like the name of a bully to me. I don't know why; it must be some childhood association I have with the name.
I like
Louis pronounced both the French and English way, but where I'm from it would be said "Loo-ee". I also love
Lou as a nickname - it would be an honouring name for me as well, so
Louis is the clear winner.
For me:
Louis BaptisteLouis FerdinandLouis Jules - ok, I love that one. So fun.