NOT considering Bizet's "Carmen", which opera by a French composer, do you consider TO BE THE BEST?

Of the three excellent choices you posted, Alberich, I'd go for Offenbach's Les contes d'Hoffmann. My personal favorite French opera, though, is Gounod's other great - Romeo et Juliet (not all that frequently performed either but full of wonderful music. Even casual opera fans would be familiar with Juliette's walts, Romeo's balcony scene, and the love duet, I think).

Debussy's Plleas et Melisande is a great work indeed. I guess it isn't as popular to casual opera fans because it actually demands more attention from its audience (no instant gratification to be had there. You have to be quite into chromatic symphonic music to 'get' what Debussy had put into that show).

Berlioz's Les Troyens is wonderful, especially when you have great cast for Cassandra, Dido, and Enee (I definitely recommend the DVD from Paris with Anna Caterina Antonacci, Susan Graham, and Gregory Kunde). I wish it could be staged more but in costs a lot to produce that big and long an opera with that demanding a music for the 3 leads.

--Added later--

Just noting my surprise that it took so long before someone mentions Massenet.... and it's his rarely performed Thais instead of the standard repertoire Werther (or Manon)! :o)

The most compelling French opera for me, though, is the undeservedly obscure Les dialogues des Carmelites by Francis Poulenc. I guess it suffers from the same illness as Pelleas et Melisande does; being a through-composed dramatic work without 'catchy song-like' moments for casual opera goers to hum to afterward.

Also, even though I like Gounod's Romeo et Juliette best (along with Carmen) the one French opera I'd love to see/hear live once before I die is actually by an Italian composer (who was living in Paris at the time), Rossini's Guillaume Tell (William Tell)! :oD

I adore Debussy's 'Pelleas and Melisande'. Of course, 'Carmen' is a huge masterpiece and it's tragic and ironic that Bizet died before he could be aware of what a tremendous success it would be. How sad!

I am not a great fan of Berlioz's operas. As great a composer as he was, Berlioz lacked the melodic lyricism to make his operas really work for me. They also go on for rather a long time! Rameau must surely be one of the greatest of French opera composers, even though he came to the form quite late in his career. I have heard (rather than 'seen') several of Rameau's operas and have loved them all. Do dip into them if you can - I think you might be pleasantly surprised. Some them include:

Les boréades

Castor et Pollux

Les fêtes d'hébé

Hippolyte et Aricie

Les Indes galantes

Zaïs

Zoroastre

My favourites, though must be Ravel's two one-act operas 'L'heure espagnol' and 'L'enfant et les sortilèges'. They are both somewhat surreal in their own ways but are enchanting and full of some of Ravel's most glorious (and yet unheard) music.

Wow, another noodle-scratcher!

Nominate a different one ... perhaps that poor German fellow who decided to do some work in Paris. C. W. Gluck and "Orfeo ed Euridice"

No, I think I'm going to stick with ... damn, you make this hard ... either Offenbach, Gounod and Saint-Saens in that order or Gounod, Saint-Saens, Offenbach. Well, heck, Offenbach was German-born, so I'll stick with Gounod at the top.

... But then again the Gothe's story is such a classic anyway!

... on second thought I like Berlioz's "La damnation de Faust" better, so let's plunk that French composer on top. :-)

(Still keeping Carmen on top of all the rest)

Pelleas is certainly at the top! It's incredible - I watched a DVD, not recently, but I definitely want to watch it again. There's this fantastic video of Messiaen talking about it to a group of students: http://www.youtube.com/watch?v=GSWatsiBErU

There are also Ravel's two short operas - L'enfant et les sortilèges & L'heure espagnole, which are great operas!

There's also Berlioz's Les Troyens, which I haven't seen but have heard it's great.

That's all I can think of for now.

Since the French do froth better than anyone, I'm going out on a limb and say Offenbach's Orpheus in the Underworld. Total p*** take of his illustrious forebear's take on the same legend. There doesn't seem to be a youtube link available for the part in Act 1 where Eurydice becomes very annoyed with Orpheus trying to play 'I have lost my Eurydice' (Gluck) on his violin:-

'Mercy, mercy, ah!

It's deplorable

It's frightful,

It's so boring

It's so irritating, ah ah!'...and so on

I'd swop the whole of any other French opera for one aria by Offenbach.

My personal favorite is "Thais" by Jules Massenet.

After seeing "Samson et Delila", I could only say that I had seen an excellent performance of a mediocre opera.

Definitely Les Contes Des Hoffmann. I love to sing the four roles! It was one of my first roles to sing on stage, and so I always feel slightly melancholy about it - but always happily! Haha, an oxymoron!

You are forgetting about Rameau, and (if he can be counted as French), Lully. Baroque opera in France was very different to the Italian, but just as good.

La voix humaine - Francis Poulenc to a libretto by Jean Cocteau

Benvenuto Cellini stands out for me.

[EDIT] in support of I .Jones

"La damnation de Faust"

For voices, and chorus written by Hector Berlioz (he called it a "légende dramatique"). ..performed as both. free-form oratorio and as an opera"

as per the wiki page