Mulholland Drive (dir. David Lynch)
This or Twin Peaks: The Return is David Lynch at his best, and honestly a coin toss could have decided this slot. A perfect mix of surreal and heartfelt (or if you prefer, heartbreaking.)
Spider-Man 2 (dir. Sam Raimi)
My token nostalgia pick. It may not be the best superhero movie, it may not even be the best Spider-Man film (though I would still say it is, not having seen Far From Home.) The most inspirational of my favorites, this movie taught me a courseload on dramatic writing and engaging action. This one still holds up, and always will.
Perfect Blue (dir. Satoshi Kon)
It was hard to choose just one Satoshi Kon film to represent his body of work and why I'm a fan of it, but at the end of the day it has to be the one with the most straightforward story and mainstream appeal: Perfect Blue. Many people drew similarities to Darren Aronofsky's The Black Swan, which came out 13 years later, but it lost the zanier edge of Kon's masterwork, among many other important details -- not to mention the stunning, at-times mindbending animation.
The Blair Witch Project (dir. Eduardo Sánchez)
I appreciate this film immensely, and still enjoy rewatching it every October. A testament to independent filmmaking and the power of editing, it's still somewhat difficult for me to explain its appeal outside those aspects. I just love this movie, man, and it's inspiring to me in the same way Clerks was inspiring to so many others.