Chikorita, Bayleef, and Meganium are the first Pokemon I ever had in my first Pokemon game, Crystal.
Obviously, they hold a special place in me.
But not only that. I'm just great with it too.
Sunflora is also good, because I refuse to call any Pokemon bad based on stats. Strategies can turn the tables around.
In HeartGold, I've defeated each Gym Leader with a Pokemon just their Pokemon's level average with a weakness to the Gym Leaders type, and it was a solo without any items or hold items (I like taking that challenge).
I did the same thing with my Meganium, and Meganium soloed the whole of Red's team in game, without any healing items, hold items, anything, and without any switch or help from other Pokemon.
I don't care that its attack stat is not as good. It one hit Ko-ed all six of Red's Pokemon when it was at level 90.