I would say the most popular ones are the ones that someone is going to bother to spend the money to counterfeit. Most niche fragrances are not popular enough to make it worth someone's while to counterfeit them.
Not even all the Creeds...e.g., there are fakes of Green Irish Tweed, but I don't know of fakes of Fleur de Thé Rose Bulgare.
Somehow I doubt that Encre Noir is that popular.