People will say that I keep praising Korean at the moment, but I personally find their Laurent Perrier one of the best (and certainly more expensive) J choices - almost all airlines chose NV in J and usually mainstream brands. Of such 'mainstream' maisons Champagne, Taittinger, Veuve Cliquot, Bollinger, and Laurent Perrier are my favourite and I can't think of any airline serving one of the first three. A few airlines occasionally servce Roederer which I personally like a little bit less but is also very good.