This is hard to answer, if we’re allowed to name only one movie. I like many genres. So I’ll cheat and mention my favorites from each genre I like:
Western: The Good, The Bad & The Ugly (1966).
Crime/gangster: Goodfellas (1990).
Animated/anime: Your Name (Kimi no Na wa, 2016).
Martial arts: Shaolin Martial Arts (1974).
Sci-fi: Aliens (1986).
Horror: Suspiria (1977).
Comedy: Top Secret (1984).
Edit to add:
Musical: Saturday Night Fever (1977).
Jim
I understand all of these refrences
Seven Samurai
I have 100's of Japanses movies (mostly Samurai with some Anime and Ganster mixed in).
I'm currently rewatching the Zatoichi series (27 movies).
I've also recently enjoyed the Tarantino and Coen Westerns
Katsu Shintaro's older brother, Tomisaburo Wakayama ain't to bad with a sword either(Lone wolf and cub).
Some say Wakayama was the best. Or maybe Konoe Jushiro.