I'm a weirdo when it comes to retro anime, because the 90s is actually my least favourite decade of the pre-2000s Japanimation scene by far. My favourite time for anime was in the 2000s, but, as I've gotten older, it's clear to see how most of my top shows were developing upon a foundation laid in the 70s and 80s. To wit, some of the anime I love from before the turn of the century is:
Miyuki, the 1980-84 series by noted sports mangaka Mitsuru Adachi. This is a gloriously-retro romantic comedy series about a young man who falls in love with two young women – both named Miyuki! To complicate matters, at the beginning of the series, one of the girls is revealed to be the protagonist's step-sister (non-blood related, of course), which puts a strain on both their familial and romantic relationships.
The show chronicles this trio's day-to-day adventures in suburban 1980s Japan alongside their group of highschool chums. It's extremely sweethearted and endearing, with some truly wonderful, blissfully-nostalgic artwork and music.
Miyuki has been my comfort series for years now, and I love them both. (Interesting fact: This show was Kitty Films' next series after Urusei Yatsura.)
Giant Gorg is a phenomenal 1984 adventure series about a group of scientists who discover a colossal, ancient robot on a mysterious remote island in the Pacific. An evil military organization is trying to capture the robot for its own ends, so our young protagonist and his friends must hold them off – and learn a little something about themselves along the way.
I really like this show's main cast – the boy hero is very well-written in that old cartoon way, and every single protagonist and antagonist is likeable. The relationship between the robot and the cast is also, in some way, very cute, and there's plenty of mystery and high adventure abound. A few years ago, Giant Gorg was very obscure, but it's seen a lot of attention over the past few months, and recently got a full remaster by Discotek Media.
I LIKED IT FIRST, THOUGH...! 
Speaking of giant robot anime, I also need to mention 1981's
Golden Warrior Gold Lightan, because it's probably the single most important and influential mecha show ever. This series was made to promote a toy with an interesting gimmick: it changed from a robot to a Zippo lighter, and back again. This ushered in a huge trend of "transforming" robot toys in Japan, and, the year it ended, some Hasbro executives saw the toys, and decided to create a little franchise called
The Transformers.
The show is a very fun action series about the titular robot and his friends – a group of quirky schoolchildren and their immature teacher. Every episode centres around a giant robot battle as Lightan fights villains from the Mechanical Dimension. It's as classic as mecha anime gets, and has earned a spot in both history and
Tatsunoko vs. Capcom.
Alright, just because I like you so much, I'll include one '90s show, here:
Buttobi CPU, or, as I've known the series,
I Dream of Mimi. This is a little three-episode OVA series about a high school student who purchases a "computer" on the black market, only to discover that he's bought a robot girl, instead! The girl, Mimi Takaoka, now wants nothing more than to live a normal life with her new boyfriend, but is hunted down by a cadre of fellow androids who she has to battle
over the Internet!
Technically speaking, this show is kinda softcore pornography (there's some on-screen sex that's played for laughs), but it's just so adorable and silly that I can't help but love it. All the characters, main and secondary, are really cute, and there's a lot of neat sci-fi imagery and concepts throughout. It's also really, really funny, and it's easily my favourite entry in the "magical girlfriend" genre. Great theme song, too!
Finally, let's end on the grandaddy of all action anime:
Sabu and Ichi's Detective Stories, coming to us all the way from the futuristic space-year of 1968. This is a black-and-white episodic series about a young samurai and his blind monk mentor solving crimes and righting wrongs in feudal Japan. The stories are ultra-dramatic, like watching kabuki theatre, but very, very gripping.
I love early TV anime, and, alongside the original Cyborg 009, this is probably the finest example of it. The show was airing
before they figured out how to animate moving water, so in certain atmospheric shots, they just filmed some live-action footage and superimposed a drawn character over it. I watch it in the dead of night, right before bed, and it's like going into another world. Every animated action series from Japan is, in some way, an imitation of Sabu and Ichi.
And that's that! The thing I like most about pre-90s anime is that there's no ego from the creators – no post-modern, ironic, self-aware, passive-aggressive pablum, like all media is today – just endearing, well-crafted writing, artwork, music, and voice acting. I'm in love with old cartoons and anime, and, with great shows like these, I'll never get tired of 'em.
U-LYS-SEEE-EE-EE-EE-EES, NO ONE ELSE CAN DO THE THINGS YOU DO-OO! 
< My name's Nono, small robot you know, friend of Ulysses! 
