My first Pokemon game was Silver, then Crystal, and both times I picked Cyndaquil. This was around the time when I picked Pokemon less for skill and type and more based on adorable features. And Cyndaquil was simply too cute to say no to. The fact that he evolved into such a bad-ass (Quilava, then Typhlosion) just made it all the better. So I grew to prefer fire types over the others. Also, I found that it is easier to catch Grass and Water type Pokemon, but near impossible to find a Fire type. Just my opinion.
The ultimate starter Pokemon, however, is Pidgey. In all the games where there was a Pidgey available to me, I caught him. Pidgey may appear to be annoying at first, with just Tackle and Sand-Attack, but Pigeot is the best asset to any Pokemon game.