Kanto Pokémon mainly for me.
Charizard: No need for explanation.
Bulbasaur: Ever since his first appearance in the anime, he was one of the best.
Sceptile: They gave him a really good personality, through all evolutions. Just a shame he's at Oaks lab now, and will rarely be recalled.
Corphish: He sort of had that hyped, fiesty style. I liked that, but it would of been great if he had evolved. For Ash's benefit.
Butterfree: In the short time Ash had Butterfree, he made it worth the watch. Ash's first Pokémon caught, when he left with the Pink butterfree. I'm sure a lot of people cried.
Snorlax: Snorlax gets recalled every now and then, and I like that. A strong Pokémon and came through in many battles for Ash, Orange League, Johto League, Battle Frontier, you name it.
Pidgeot: is definatly a great, but for one reason. Our hatred to Ash for releasing it, that episode is one of my all time favourites when it evolved. It was mainly used to burst Rocket's balloon, but shown it's loyalty to Ash when it flew him to the match against Richie. Still wish we could of seen more of Pidgeotto's personality.
I would say Pikachu.. but it's a yes and no. Had some good moments, some lame moments, and some sad moments. But I'm not feeling it.