I have to make clear that I don't specify "season 3" because the early Transformers cartoon was a good show that declined in quality after Optimus died. No, it's just that season 3 is the only season of the original Transformers cartoon that I give a damn about, and how. The original Transformers cartoon never changes in quality, but I prefer the characters and settings of the third season, which were part of my first fandom. Because of that, no matter how much my taste in media gets refined, I can still watch these cartoons.
The Transformers: the Movie was the first G1 thing that I ever watched. I picked it up in 1998, wanting to have context for the references in Beast Wars. I loved it at the time, and still do. The film is noisy, incoherent, and half-baked. Its foreshadowing is laughable, the cast shift is jarring, and it is unconvincing that suddenly now characters would die from blows they walked away from in the TV show, especially with such a weak sense of escalation, but it's so much fun.
I don't give a shit about the older characters, and this movie just looks so good being itself, with lots of shiny, colourful robots having adventures in excitingly weird alien environments, to the tune of earwormy hair-metal and synth. TF:TM just has this borderline hypnotic effect on me, and I can just sit and watch it, eyes glazed, up until the very end of the credits.
Season 3 had more of the same, but it was different. Although the art as less shiny, it was much more interesting, character-wise. Getting a season to themselves, the "new" Transformers were pretty awesome. Rodimus Prime, with his sarcastic insecurity, was my top favourite, but I liked most of the main cast, except for kid sidekicks Wheelie and Daniel. To this day, I prefer these renderings of the characters over any other interpretations, even if the re-imaginings may be technically better-written, or appeal to a broader audience.
The only other popular 1980s cartoon I enjoy is The Real Ghostbusters (though Inhumanoids had some cool parts), but I don't look down on fans of He-Man, ThunderCats, etc, because it's pretty much the same thing I'm doing here--a series just gets you in a certain way and you can't let go of it.
That doesn't make the G1 Transformers cartoon good, however. I can watch season 3 through a gauze of nerdy nostalgia, but once I get out of that comfort zone, the cartoon becomes just painful to watch. There's bad voice acting, bad animation, nonsensical plots, and poor world-building. It's a dumb show, designed to sell toys.
But there's just a tiny, flickering spark of warmth to the series that lets me understand why I still enjoy it. There are character moments that seem genuinely heartfelt and "real", mostly Rodimus' difficulties, and the way Cyclonus acts in "Webworld" (still the best episode). The settings are wonderfully weird, too, with the alien and robot designs being equally interesting. I wouldn't change a thing about it, including the callous bumping off of the old cast, but it's not something I'd loudly identify with, or recommend to another adult.