Brandy, and its other forms, such as Cognac, Armagnac, and Calavados, is a liquor distilled from fruit juice, and what's good to drink is mostly a matter of personal taste. In general, French cognac, especially that marked as V.S.O.P. or Napoleon, is considered the best for drinking neat.
Cognac is distilled in the region in France of the same name, and Martell, Remy Martin, Hennessey and Courvoisier are considered premium brands. It is available in V.S., or Very Special; V.S.O.P., or Very Superior Old Pale; Napoleon, or X.O., which stands for Extra Old; and Hors d'Age, which means that it is more than 10 years old. Older brandy is generally smoother. American brandy, such as Christian Brothers and Korbel, are sold in similar grades.