Definitely the fire starter (Fennekin). Mostly because I just love the overall design idea of the fox, as well as the fact that fire starters are the ones I usually pick. Which starter are you gonna pick? Also, based on the screenshots/videos I've seen so far, I think the 3D looks pretty good at the moment. X and Y is gonna be awesome by the looks of it.
Right now, I currently don't own one just yet. But I'm planning on getting one eventually so I can play one of the new Pokemon games as well as a few other games I've had my eye on lately (such as Professor Layton and the Miracle Mask).
Also, I sometimes go for the water and grass starters too when I'm playing the games again. Mostly just for a bit of variety.