Torchic, because when it evolves into Combusken it becomes not only fire-type, but it also becomes fighting-type, which will help you in battling, especially the normal-type Pokemon. But also, there are some risks to evolving it. For one thing, it becomes weak to bird Pokemon, because fighting type is weak against flying type. And the fighting moves won't help much when you're fighting a ghost Pokemon, because they're along the same lines as normal moves.
But other than that, Torchic is a good starter Pokemon to have. Why do I know this? I started with a Torchic! :)