Cyndaquil!
I started out with Chikorita on my first Crystal playthrough, but then I soon discovered how awesome Cyndaquil could be. Its moveset, for one thing - with the ability to learn Thunderpunch and Earthquake once it evolves into Typhlosion, it's a Pokemon that could knock out a LOT of other types, including some of its weaknesses!
And yeah, I usually go with the fire types as my starters (Charizard, Typhlosion, Blaziken) at least until DPPt, when NONE of the starters appealed to me - I started with a Chimchar, but didn't like how it looked.