20s - Un Chien Andalou (Dir. Luis Bunuel)
30s - Vampyr (Dir. Carl Theodor Dreyer)
40s - Paisan (Dir. Roberto Rosselini)
50s - The Searchers (Dir. John Ford)
60s - The Good, The Bad, and the Ugly (Dir. Sergio Leone)
70s - Alien (Dir. Ridley Scott)
80s - One From the Heart (Dir. Francis Ford Coppola)
90s - Cure (Dir. Kiyoshi Kurosawa)
00s - LOTR (Dir. Peter Jackson)
10s - Interstellar (Dir. Christopher Nolan)

40s and 80s picks

My 20s-60s picks are probably still v liable to change though since there isnt much I've seen from those decades lol

Though I do love every film I picked here

50s - Vertigo
60s- The Graduate
70s- Taxi Driver/Carrie
80s- The King of Comedy
90s- La Haine
00s - The Departed/Mulholland Drive
10s- Waves/The Social Network

20s passion of Joan of arc
30s M
40s citizen kane
50s 12 angry men
60s battle of Algiers
70s Network / Barry lyndon
80s mishima / come and see
90s thin red line
00s there will be blood
10s social network