I have eaten a few croissants in the past month, and none have beaten Markt's croissant. I don't know if they're from Balthazar, but they're the perfect flakey, buttery croissant.
Since then, all I have had are terrible imitations, mostly bread-like dough shaped into the croissant shape.
Zago's - breadlike
Corrado - breadlike and expensive
Hot and Crusty - breadlike
various hole in the wall bakeries - terrible! terrible!
Where, oh where is that perfect croissant?