My first was Sailor Moon, on TV as a little kid. But it wasn't until me early teens that I really got into the hobby proper.
I got introduced to the Dragonball manga by a friend when I was 12. That lead to me watching some DBZ when I got good internet (it never aired here).
Around the same time I discovered Ragnarok Online and through that was exposed to the anime community (it was very much a weeb game). Curious and hungry for more after DB and DBZ, I watched entry level things of the time like Chrono Crusade, D.N Angel, Matentai Loki Ragnarok, etc. I got into Naruto too through a friend in middle school.
The anime had just started airing and I think there were like 8 episodes subbed out. I already knew about the manga, and since I couldn't find many episodes to download reliably through the P2P I was using, that got me into reading scanlations. Always having been a fan of comics and books, I got into that big time, especially when e-readers like OneManga popped up. Anime was doomed to taking a backseat from then on.
Even today, I don't really watch much.