Most of my favorite Gen I Pokémon are the birds: Pidgeot, Farfetch'd, Fearow, those guys. When it comes to battle, Pidgeot is my favorite Gen I mon, because 1. it's Bird Jesus and 2. it has an awesome Mega Evolution. Design-wise, however, it's a close one, but I'm going with Farfetch'd. It just...looks so amusing. It's a duck with a spring onion. I love it. There are lots of others I find almost as appealing as Farfetch'd, but Farfetch'd takes the cake. I just wish it was more useful.