Limited to one film a director for sheer diversity reasons (I didn't want to comprise a list solely of Lynch, Herzog and Godard), mine looks like this, in chronological order:

Citizen Kane (1941; Welles)
Le samourai / The Samurai (1967; Melville)
Week-end / Weekend (1967; Godard)
The French Connection (1971; Friedkin)
Aguirre, der Zorn Gottes / Aguirre, Wrath of God (1972; Herzog)
Don't Look Now (1973; Roeg)
The Conversation (1974; Coppola)
Eraserhead (1976; Lynch)
Taxi Driver (1976; Scorsese)
Manhattan (1979; Allen)

...dot com bold typeface rhetoric.
You go clickety click and get your head split.
'The hell you look like on a message board
Discussing whether or not the Brother is hardcore?