I'm probably gonna choose Cyndaquil to start off, and on my second run of the game, trade all three starters. Technically speaking, Cyndaquil was my first ever pokemon, since Gold version was my first ever game, and it was my starter.
And sheesh, I see much hate towards Chikorita =P
If it weren't for my sense of nostalgia, I'd probably start with Chikorita, cause I always loved Meganium (after I played through Pokemon Colosseum on gamecube)