One ring to rule them all just cannot be. It's not which color you prefer over others question, nor is moral/immoral binary choice.
Breezed through the thread, some were already noted as awsome, however some were for whatever reason skipped. Hopefully I won't repeat a title, but seems to me too many were not mentioned yet.
IMO each of these deserves to be watched before dying and I'm aware you've never even heard of some (tried to sort them per release year):
The Shining (1980)
Butcher, Baker, Nightmare Maker (1981)
Das Boot (1981)
Escape from New York (1981)
Scanners (1981)
Blade Runner (1982)
Mad Max 2: The Road Warrior (1982)
Star Trek II: The Wrath of Khan (1982)
The Verdict (1982)
The Meaning of Life (1983)
Zelig (1983)
The Brother from Another Planet (1984)
The Killing Fields (1984)
Threads (1984)
Back to the Future (1985)
Brazil (1985)
Ran (1985)
To Live and Die in L.A. (1985)
Jean de Florette (1986)
Labyrinth (1986)
Little Shop of Horrors (1986)
Man Looking Southeast (1986)
Manon of the Spring (1986)
Wings of Desire (1987)
Evil Dead II (1987)
My Life as a Dog (1987)
Akira (1988)
The Miracle Mile (1988)
The Vanishing (1988)
They Live! (1988)
Batman (1989)
The Decalogue aka The ten commandments (1989, aired as miniseries although it's de facto a superlong movie broken into parts)
The Killer (1989)
This is not some full list "watch only and ignore everything else" from 80's. But if someone is going to dig through 80's goldmine of movies, start with these.