Negroni
Equal parts gin, Campari and sweet vermouth. Three ingredients, no measuring gymnastics, and nowhere to hide.
Martini
Gin and dry vermouth, stirred cold enough to hurt. Every argument about this drink is really an argument about one ratio.
Manhattan
Rye, sweet vermouth and bitters. Two ingredients and a dash, and the vermouth is the one that decides whether it works.
Old Fashioned
Whiskey, sugar and bitters — the drink that defined the word cocktail, and still the best argument for it.