The first episode I saw was "Troll Bridge", which wasn't one of the best by far (IMHO that was definitely episodes like "Knock Knock", which felt like little movies rathe than cartoon episodes), but it was fun and a bit whimsical.
Even though it's a different beast (no pun intended) to what I wanted from Ghostbusters stuff, I loved it and watched the hell out of it until the next episode came on the following week. This was 1988. I was hooked as soon as I saw this. here it is, and despite its faults, I think it's lovely. I must talk about GB again soon.