Just tried the relative newcomer's croissant at Chaumont (in Beverly Hills; croissant is pictured) last week. Comparing it with my current croissant fave at Maison Giraud (in Pacific Palisades):
Butteriness: The edge goes to Maison Giraud.
Bite: Chaumont has a slight advantage.
Flakiness: Gotta hand it to Chaumont.
Aroma: Maison Giraud wins in this category.
"French"ness (for lack of a better phrase): A virtual tie.
It's too close for me to call. Someone else cast the deciding vote. I suppose we're fortunate to have this problem here in L.A...