Thinking about it, I've realized that I like a lot of his Pokemon.
Top favourites are; Torkoal, Sceptile, Froakie, Squirtle, Bulbasaur, Muk, Infernape, Corphish, Heracross and Torterra. Most of them are for their development like Infernape, Squirtle, Bulbasaur, but the rest are because of their personalities.
Oh and early seasons Pikachu for his comic relief.
Before evolving Snorunt, Caterpie, and Phanpy were up there, but once they evolved they lost all of their personality and just became boring.
Same with his bird Pokemon, none of them are interesting and they're just plain.