My all-time favorite from Mylène Farmer is and will remains the song
Point de Suture.
I just find it beautiful, like a ballad level 99, with a voice and words that make me shiver everytime I hear it. The sound of the music is just hypnotizing.
Check out the live of this song :
https://www.youtube.com/watch?v=07B8ygF-Ht8
Tremendously amazing, yet very simple.