I remember when my brother first got "into" pokémon and introduced me to all of the first set through his books. The one I instantly loved best was Ninetales, and to this day it remains one of my top favorites, obv!
It does, however, risk being dethroned by Manectric. :0
I think my brother's first favorite was Blastoise. And my friend told me his first was Golduck. ^--^
Then every time a new set came out, I'd immediately have a few new instant favorites. Others took me a little time to warm up to.
But when the last group arrived, and I saw the sprite versions of them all? I was automatically smitten by my little friend here:
For personal reasons. I mean, it was instant LOVE. I went: "Looks like a dog...combination of 2 of my favorite colors, a yellowy-green and a bright blue...looks very, very cool, and beautiful....o.m.g....!" There was no contest for me in that set.