Mai Tai

Two rums, lime, orgeat and curaçao. No pineapple juice, no grenadine, no umbrella required.
Negroni

Equal parts gin, Campari and sweet vermouth. Three ingredients, no measuring gymnastics, and nowhere to hide.
Whiskey Sour

The sour template in its most familiar form — and the easiest place to learn what egg white actually does.
Old Fashioned

Whiskey, sugar and bitters — the drink that defined the word cocktail, and still the best argument for it.