Not in a particular order:
All that Jazz - Bob Fosse was one of the most gifted film makers duriung the past century. It’s too bad that the musical genre was almost dead when he made his films, otherwise, his influnce would have been even greater, mostly because he did choreography for the camera, not an audience. AtJ is the best, IMO, being semi-autobiographical and also showing that it’s quite possible to tell a coherent story without a linear narrative. I don’t know if Tarrantino has watched it a lot, but it wouldn’t surprise me.
Romeo+Juliet - Baz Luhrman did what no one alse has managed. Make a version of Shakespeare that’s relevant today and which captures the fever, insanity and stupidity of what it’s like to be in love and a teenager. I think it’s the best screen adaption of any Shakespeare play, being true to the source material, while being totally modern at the same time.
The Ox-Bow incident - mostly because I saw it when I was about ten and I’m still a firm opponent to the death penalty.
Star Wars - a tad predictable, but I was 16 when it was realeased and for anyone who came in contact with it afterwards: you just can’t imagine what an impact it made. Especially on this geeky kid who were totally into SF and fantasy at the time. There’s an episode of That 70’s show which actually captures it quite well.
North By Northwest - the Double Chase perfected. It’s the quintessential Hitchcock movie and Cary Grant is perfect. James Mason is a very good villain, soft spoken and not sadistic. An elderly gentleman and therefore so much more frightening.
Blazing Saddles - the mother of all parody movies.
Chinatown - Polanski and Towne made the best Film Noire about 30 years after the glory days of the genre. Is it a hommage? Or maybe a movie that coudn’t be done in the 40’s because of the political implications. It has everything, including the bad guy getting away with murder.
Jungle Book - the first movie I saw in a theatre.
Cross of Iron - Many would pick ‘The Wild Bunch’, but I really like a movie told from a German POV, but made with American actors - who don’t speak English with a heavy fake German accent. It’s a great movie about the futility and madness of war.
Invasion of the Bodysnatchers - I don’t know if Don Siegel realized it when he made the film, but it’s the best horror flick ever. Almost 50 years old and it’s still scary. Frankenstein and Dracula are fun, but not something to give actual nightmares. But the claustrophobic and paranoid atmosphere of Bodysnatchers is still palpable. I also think it made the original mold for most horror films that followed.