This is just a warning- anything other than my #1 Pokemon is pretty much interchangeable, since there are a lot of Kanto Pokemon that I like, but none really more than the others. Also, I'm going from 10-1, since I like to be different.
10. - Starmie. I've really never used Starmie as much as I'd like to, as I've generally got a good Water Pokemon by the time they're accessible.
9. - Lapras. Rarely have I ever used a Lapras in the games, but it was the TCG and anime that put it high on my list.
8. - Arcanine. As explained later, Arcanine could be as high as #2 on this list, but right now it settles in here.
7. - Articuno. Only behind Rayquaza in my list of favorite legendaries, I've always loved Articuno since the discovery ofthe Mind Reader + Sheer Cold combo.
6. - Golduck. To be honest, I never used Golduck in the early games- only using one temporarily in FR, until having one on my team full time in HG.
5. - Gengar. The original Ghost Pokemon has always been high on my list, even if it took me years to get one through legit means.
4. - Blastoise. While Charizard and Venusaur are good, Blastoise has always been my favorite of the Kanto starters, and is probably in my top 3 of all available starter Pokemon to date.
3. - Pidgeot. I don't use it as much any more, but the Pidgeot family was a staple in my Pokemon games for the first 4 generations, whenever they were available.
2. - Ninetales. I've always liked Ninetales, but I've got a love/hate relationship with it, since I flip-flop on whether I like it or Arcanine more. 80% of the time though, this spot goes to Ninetales.
1. - Butterfree. Not only my favorite Kanto Pokemon, but my favorite overall. It's also the only Pokemon that's held importance to me in the anime, TCG, and games, which is why it's at the top of my list.
Honorable mentions go to Clefable, Marowak, Hitmonchan, and Chansey, who could all crack my top 10 depending on my mood at the time.