I didn't get into Pokemon until I was 14 (about 2 years ago) when I bought a GBA and my friend gave me her copy of Crystal (she didn't have anything to play it on anymore)
So Crystal was my first game, and I chose Chikorita because I thought it was cute. However, I beat 2 gyms then decided to start over and chose Cyndaquil (beat the whole game with that thing, I didn't know about teams)
Now I usually choose the grass starter for my main game, water for the opposite, and fire for the later released 3rd one.
I did get some of the other games over time, so here are my starters for the games I have:
Blue: Bulbasaur
Yellow: Pikachu (obv)
Silver: Totodile
Crystal: Chikorita
Ruby: Treeko
Sapphire: Mudkip
LeafGreen: Bulbasaur
FireRed: Charmander
Emerald: Torchic
Diamond: Turtwig
Pearl: Piplup
White: Snivy
Black 2: Tepig
X: Chespin
Y: Froakie