Boris Gudenuf
Deity
Surprised you didn't say Queen Elizabeth I which would make more sense than both of them. That being said I have gotten used to CdM, but still would want another leader to give France a different direction.
Just the legitimate rulers of France give the designers a huge variety of directions in which to go:
Francis I and Henry IV for military, the former related to First Use of field cannon and the latter a most Religious militancy or even a way to purloin effects from other religions ("Paris is worth a Mass" - or a Chant, Revival Meeting, Seder or Haj...)
Louis XI (The Spider King) for spy or diplomatic action
Louis XIV for Culture or possibly a Bonus to Wonder Building
Napoleon I, but instead of more military, one could emphasize his rebuilding of France's administrative and legal structure
Louis Napoleon - given his rebuilding of Paris, perhaps the game ability to replace, move or rebuild Districts?
Clemenceau and DeGaulle for 20th century leaders with diplomatic and military leanings.
While European Civs are passe compared to the 'exotic' Civs, the fact is that France has a rich variety of leaders for almost any set of Uniques you want to bestow...