among American "best off" lists you'll find all over, there a couple of films mentioned at the top so often, that it is almost (almost!!) fair to say these films ARE the best ever.

(btw these lists differ mostly in regard to the amount of 'classics' (pre 1960) in the list, like the AFI list who has a lot)

CITIZEN KANE
CASABLANCE
THE GODFATHER
LAWRENCE OF ARABIA
GONE WITH THE WIND
VERTIGO
2001: A SPACE ODYSSEY
THE WIZARD OF OZ


here's the AFI list
http://www.geocities.com/Hollywood/Screen/6601/

Years with most AFI films = 1939 (5)
Most Represented Directors=Steven Spielberg (5 )
Most Represented Actors= Robert Duvall (6)
Most Represented Actresses=Katherine Hepburn (5)

Color=39
Black and White=61
Silent=3

and quite often as well:
TAXI DRIVER
PSYCHO
APOCALYPSE NOW
SINGIN IN THE RAIN
THE GRADUATE
ITS A WONDERFUL LIFE
ON THE WATERFRONT
SOME LIKE IT HOT
SUNSET BLVD
ONE FLEW OVER THE CUCKOOS NEST

international films:
8 1/2
BATTLESHIP POTYEMKIN
LA DOLCE VITA
THE SEVEN SAMURAI
PERSONA
METROPOLIS
LA REGLE DU JEU
SUNRISE
RASHOMON
PASSION DE JEANNE D'ARC
BOUTTE DE SOUFFLE

the new top-ten-lists-overall-standings are:

The Godfather: 104
Scarface: 91
The Godfather II: 73
Pulp Fiction: 58
Memento: 44
Goodfellas: 42
Fight Club: 36
Usual Suspects: 25
Return of the King: 22
Fellowship of the Ring: 21