The very first ... I belive it was transformers but there people that told me Transformers wasn't an anime, I can't say for sure because I was too young to remember.
I saw Zillion when I was a lot young too, but only one episode and I don't remeber a thing, so I'm not sure it counts.
The one I'd say I remeber well is Akira, which I hated. But thankfully that didn't made me hate animes at all, I've always been kind of open minded, so when I saw an anime I liked I was hooked into this like crazy.
The first anime I liked like hell was Saint Seiya.