Oh man... I think I'll end up spamming this thread on all the kinds of shows that I used to watch.
To start, Saturday Morning Cartoons had some meaning back in the day. Teenage Mutant Ninja Turtles, the classic version, The New Ghostbusters, Bobby's World, Rocky & Bullwinkle, Loony Tunes, the list goes on; and that was before Nick Jr. became it's own segment on Nickelodeon, as well as other shows that were starting on there at the same time.
As with that, I initially thought Lupin III was the first anime I really watched, but as it turns out (thank you Tropes) Nozzle and David the Gnome were the fist ones I have actually seen as they premiered on US broadcasts on Nick Jr., along with Muppet Babies (which looking back, was still rather funny. I mean, it's the Muppets.). But as if I were only sticking to that part of Nick at the time (I mean, I was watching turtles armed to the teeth and such; I wanted more), There was also The Adventures of Rin Tintin, Inspector Gadget, Rocko's Modern Life (now that it all comes back to me; holy crap was I naive), Ren & Stimpy (which since I managed to catch all the episodes shown at the time; I'm resilient to nightmare fuel apparently), Tiny Toon Adventures, an assortment of random cartoons like Batfink and such that were randomly broadcast, Angry Beavers, AAH! Real Monsters, Doug, Rugrats, Hey Arnold! (I figured the first seasons were the only real good ones, until they became serious, same with Doug; Disney episodes don't count), I mean, I remember the classic Nicktoons theme still and all 6 shows featured in that promo. And that's Nickelodeon in the 90s alone.
I was also a rather dedicated late 80s Disney viewer when they used to air classic cartoons ranging from the B&W classic cartoons all the way to Duck Tales, Chip & Dale's Rescue Rangers, Talespin, Darkwing Duck, the list goes on until Goof Troop lost my interest, and Nick was playing more interesting things (plus, Adventures of Pete & Pete (Live action awesome show of pure awesomeness; still. I have all the episodes.)). Anyway, most of the cartoon shows there caught my attention more than their live action blocks big time (never was a fan of MMC nor KIDS Incorporated. *shudder*, still irks me remembering the theme songs and such).
And as for any other shows I forgot to mention, simple answer is, if it was named, I may have seen it; all the way up until the late 90s when they began changing the format big time to the lameness you see nowadays.
Oh right, I forgot about Cartoon Network. I think I've been around since that channel began. Hell, I've been around since the beginnings of [as] when Space Ghost and Cartoon Planet were the main features. Hell, while being home-schooled, it was nearly an event for everyone to stay up late to catch an episode of those shows. Again, another show so freaking epic, I just had to find a torrent of it since I couldn't find it anywhere else on DVD (at the time). Plus, with Space Ghost: "Boat Show", purely epic episode. Steve Allen, Andy Dick, musical episode, f***ing hilarious. I'm still bothered that nobody on Youtube or similar location has it posted yet.
And at the time, I wasn't as much a fan of anime as I am nowadays; never was much a fan of the Toonami blocks unless Samurai Jack was on or something. Plus, Cartoon Cartoon (when it initially began) was rather fun to watch. I underestimated just how funny those shows could get; especially since their pilot episodes aired on like a Cartoon Lunchbox or something along those lines. I forgot the name of that show; but that was where Cartoon Cartoon actually began. What caught my interest more at the time of those premieres were shows like The Tex Avery Show, and similar. Why do classics no longer air on TV anymore? Kids of recent generations are becoming pansies and not being as creative from the looks of it. Plus, try watching The Mask (not Son of), and then watch some Tex Avery cartoons; you'll find the references you need there. Just as well, those shows also showed how the creators came up with some of the jokes and ideas and some background on the developing scene of the cartoons. It was entertaining and educational of the process. And we can't forget about Freakazoid!; I think that show seemed to influence much of my actual personality now that I come to think of it.