First I have to quote David Mullen: "A very broad question..."
An easier queston would be: What are your "must-seen" movies in cinematography, and so on.
I will write down some movies. They are my "must-seen" movie because of different reasons. Some I choose because of cinematography, some because of the story, some because of the message, etc.
And I only choose one film per Director
The oldest one is "Nosferatu" from Friedrich Wilhelm Murnau. What an atmosphere!
"Le procès" from Orson Welles. For me the best Kafka adaption.
"Persona" Ingmar Bergman. Really impressive cinematography.
"Suspiria" Dario Argento. The last film, which was shoot in the technicolor system. I have seen an old british analog print. What incredible colors. Unfortunately this experience is not so good on BD.
"Il Grande silencio" Sergio Corbucci. For me one of the best spaghetti-westerns.
Another "must-seen" spaghetti-western is "Faccia a Faccia" from Sergio Sollima.
Some other italian films:
"Nuovo cinema paradiso" Giuseppe Tornatore. What a declaration of love to cinema. Definetely my favorite film. There are existing two versions in Italy. There is a longer one then the international version.
"Mediterraneo" Gabriele Salvatores. The best anti-war movie.
To come to other countries:
"Lucia y el sexo" Julio Medem. What a good screenplay!
"Le Mepris" Jean-Luc Godard. Godard in cinemascope! Normaly he shoot 1:1,33.
"Fitzcarraldo" Werner Herzog. No comment!
"The Wild Bunch" Sam Packinpah. I saw this film two times in cinema. It was a film print! This film changed cinema!
"La Haine" Mathieu Kassovitz. The combination of the story and black and white pictures is amazing!
"Valhalla Rising" Niclas Winding Refn. This film shows very good that you do not need so much dialoge then most filmmakers think!
"Le fabuleux destin d’Amélie Poulain" Jean-Pierre Jeunet. Details!!!
Three asian films, which are a "must-see" are:
"Die xue jie tou" (Bullet in the Head) John Woo. The non plus ultra Action-Epic! Very often copied, but never reached.
"Dung che sai duk" (Ashes of Time) Wong Kar-wai. You have to see this pictures photographed by Christopher Doyle! There are two versions. The Redux one is not so long. I bought in the year 2000 the asian DVD to see this film. It was very expensive and the english subs were not so good, but it worth every single cent!
"Gongdong gyeongbi guyeok JSA" (Joint Security Area) Park Chan-wook
And as a German I will recommand you two very good German speaking films. The best ones I have seen in the last years.
"Das finstere Tal" Andreas Prochaska (Austrian-German co-production). What an atmosphere, when you seen this film on a big screen and wiht a good sound system. Wow!!!
"Victoria" Sebastian Schipper. This film was shot in one shot! Ok, not a new idea, but in my opinion the best one-shot-film.
This are only a few films and only a few comments...
Hope in this list where some movies you have not seen, Jan.
Maybe we can discuss some of the films, the others and I mentioned in this forum.