Best "Old" Anime That You've Seen?

Old is subjective. I'm not really a fan of modern day anime, save some outstanding exceptions. So, what's your favorite anime from anywhere between 1970s to the early 2000s? Anything older than 15 years counts!

Some of my favorites:

Nana

Durarara!!

Kuragehime

Monster

Serial Experiments Lain

Kuuchuu Buranko

Ashita no Joe

Paranoia Agent

Detroit Metal City

Panty and Stocking

Maison Ikkoku

Legend of the Galactic Heroes