If you are looking for the traditional French singers, here’s a representative list.
Jacques Brel (sings also in Dutch), Yves Montand. Patachou, Georges Brassens, Juliette Greco, Yvette Guilbert. Piaf (yawn). I have wonderful old vinyls of them singing.
Here’s a list of more traditional, regional and pure French singers.
http://en.wikipedia.org/wiki/French_folk_music
I have no knowledge of more contemporary music.