I'm a sucker for Fire types, so naturally, when I started Emerald, Cyndaquil was my selection. Doesn't help me much in the water, but there seems to be an abundance of Grass types to deal with them and few Fire types by comparison, so I cover that base immediately.
This means I will likely choose Charmander in Fire Red. However, as I now want to push a Shiny Nincada to Generation V as soon as possible, I have to try to complete at least SoulSilver and Emerald right now, and I'm hoping to get it cloned at that point. I can hope. :)
Cyclone