Keroppi and/or Hello Kitty. I remember watching both from a very early age, though Keroppi more, if just because the channel aired it more.
Later the original dub of Dragon Ball, which I didn't realize only had 13 episodes. But I only caught it every now and then since it was frequently aired at weird times of day. Then Sailor Moon came out in English and that was pretty cool. Then Dragon Ball Z, and since I saw the first arc of the original series, I just figured I missed a whole ton of episodes due to them being shown at like 6am. I never realized they just never got brought over. Either way, Dragon Ball Z was the first anime I ever got really autistic over. I followed the story of Sailor Moon, but I never got so into it that I'd be bothered if I missed an episode.
After Dragon Ball Z, and then later Pokemon, anime got big. Pokemon got lame by the time Ash got to Johto and started giving away all his pokemon. Digimon was always better anyway. I'm still mega autistic for the Digimon anime, which I now realize was better known as Digimon Adventure and Digimon Tamers Adventure 02 is pretty good too and doesn't deserve its bad rep . Digimon holds up. I also loved Monster Rancher, but only recently learned it had a second season. I gotta rewatch the whole thing and check out that second season now. Yu-Gi-Oh was the last anime like that I got into from watching on TV. I mean I also watched Beyblade but mostly just because it was on. It didn't hook me like Yu-Gi-Oh.
Then I didn't watch anime for like five or six years (except for Dragon Ball, because my autism for that has never waned) until I was old enough to seek out the original versions and then learned they're way better. Now I can't even believe I liked those dubs when I was a kid. Just goes to show how good the originals were, that the quality could shine through even with a bad dub. And of course found a bunch of new (old) stuff to watch that never had a dub in the first place.