For Animation I would have to say the three movies by Rene Laloux.
Gandahar (1987)
Time Masters (1982)
Fantastic Planet (1973)
I'm also a big fan of Oshii, and I think the most artistic film he made was Angel's Egg (1985).
I usually go by director when I'm attributing the overall work to a single man, but I think the writer Hideyuki Kikuchi's work has produced some of the most interesting films.
Vampire Hunter D (1985)
There are actually a couple of different English dubs, and it's crucial to find the right one. It makes a huge difference even though it's a subtle aspect. This one shines above it's sequel with really crisp animation for it's time, great composition, and very creative themes. It's a classic portrayal of vampires done so perfectly right. You can feel the lore in subtle things the characters say (again, some of this is lost if you use the worse dub/sub).
Wicked City (1987)
Demon City Shinjuku (1988)
A Wind Named Amnesia (1990)
A Wind Named Amnesia is an exceptionally beautiful story set in a post-apocalypse after a wind sweeps across the whole Earth erasing everyone's memory. Everyone forgets how to drive, planes, cars, trains, and boats crash, civilization breaks down completely. Humanity basically reverts to the stone age because they even forgot how to speak languages. One man learns how to talk and meets a mysterious woman.
Darkside Blues (1994)
Darkside Blues is a really interesting hidden gem.
Leaving Hideyuki Kikuchi behind there are a few more animated films that are mind blowing.
Genocyber (1994)
Genocyber is ultraviolence to the max, psychics and cyborgs with brain and guts hanging from the ceiling. The English dub is excellent.
The Dagger of Kamui (1985)
The Dagger of Kamui is by far the best Ninja animation there is. It far surpasses the likes of Ninja Scroll.
Perfect Blue (1997)
Perfect Blue is one of my favorite movies of all time, and in my opinion it's Satoshi Kon's best work. The detail and quality of the artwork and animation looks like something that was made in 2003. The deeply psychological writing has so many layers thst it will take multiple watches to understand the extent of exactly what happened. I learn something more about the movie every time I watch it.
Dragon's Heaven (1988)
Dragon's Heaven is a shorter movie, only about 40 minutes. It's possibly the most futuristic thing I've seen in terms of how far in the future it is.
The Animatrix (2003)
In my opinion The Animatrix is better than the original Matrix. While the original gave me an epiphany the first time I saw it, The Animatrix gave me multiple epiphanies. The Matrix lost it's impact after the first watch, because it relied so heavily on a twist. But The Animatrix gets better every time I watch it. I think it has a purer philosophy of the nature of the world. The way that Neo woke up to the reality of the world didn't go beyond the actual Matrix, and explained little. But the Animatrix tells much more realistic and compelling stories.
Memories (1995)
Memories is three short stories.
Kite (1998)
I think Kite is Yasuomi Umetsu's best work. He also worked on Akira, Grave of the Fireflies, Mezzo Forte, Lily C.A.T., Kimera, Robot Carnival, Barefoot Gen, Lupin III, Angel Cop (another favorite of mine), Mobile Suit Gundam: Char's Counter Attack, Urotsukidoji: Legend of the Overfiend, Megazone 23, and Galactic Patrol Lensman. So yeah, those in my opinion are great stuff he's worked on, but he has done tons more stuff. Kite is one that he really made himself, not just worked on.
Personally I'm not a big Miyazaki fan. I think he's had a ton of influence on the medium, and been very prolific. Many animation artists consider him the greatest, but I think the writing quality of his stories lacks enough depth of insight into human psychology and philosophy.
Whisper of the Heart (1995)
This is my placeholder for Miyazaki. I think Whisper of the Heart is his most powerful story.
Royal Space Force: The Wings of Honneamise (1987)
This has a level of detail and animation quality as well as art style identical to Akira, but it came out one year prior, it also has a lot more focus on story and character relationships.