For me, Mastering the French by Neil MacDonald is far and away the best book I've read on the french. It isn't terribly new but deals with pawn structures, typical plans and ideas
I also like McDonald's Mastering the French best among the all-variations of the French books. He also has a book completely devoted to the Winawer Variation and another on the Classical and Rubinstein Variations. Someone mentioned Watson's Play the French, 3rd Ed, but neither the 3rd Ed. nor the 4th Ed. cover the Rubinstein Variation at all. I does cover the Winawer in detail.
The best book is the wikipedia article and chessbase database.he he .