Yeah, Chikorita is adorable! ^_^ I love it, even if it isn't the best fighter.
My other favorite is Charmander. It would be worth choosing just to get Charizard, though, its cuteness is a plus, too. Out of the rest, I would say Cyndaquil, just because when mine evolved, and finally became Typhlosion, then it was one of my best fighters on the games.