I bet you can guess the one.
Psycho is a masterpiece. It’s hard to argue much else. Its innovative horror changed not just the genre landscape but the moviegoing world at large. No longer was it expected to jut dip in and out of movies. What if they had a Psycho twist? You watched movies from the beginning and refrained from spoiling them at the end. This was a new code of conduct ushered in by one fantastic plot.
Alfred Hitchcock, despite his power and influence, still had his flaws (outside of his tormenting of his actresses). The ending of Psycho has some of his best and creepiest filmmaking and his most broad and inorganic.
Editor Natalie Kainz analyzes this divide, explaining the commonly-examined film for those that never got a chance to take a film appreciation class in college. Her observations are neat, quick, and, in the best trick a critic can pull, make you want to (re)watch the film for yourself.