One of the most expensive hotels in Paris :Hotel Le A

Well, that is no easy question, let me tell you. If price should be the main factor, then the Hotel Le A as they call it might be the one :) A room there will set you back more than 300 E a night, but you get breakfast for that. It's a minimalist style designed building with interiror decorations to match that. It's located on rue d'Artois