In G/S/C it was Cyndaquil. Despite being a pure Fire type, it had the best and most accessible movepool and was the only good Fire type you could find early on enough in the game due to the absence of evolution stones (ruling out Arcanine and Ninetales). Totodile was good but many of its moves were hard to access (damn tutor or breeding moves). Chikorita was an average Grass pokemon that nobody really liked because Grass pokemon weren't much good at all in G/S/C, at least not until you reach Kanto.
I always picked Cyndaquil, and added Alakazam (man, was he good back then), Machamp, Gengar, Ampharos and Quagsire to my team. In Crystal, since Ampharos was stupidly unavailable, the sixth pokemon was a HM slave.
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