I prefer the Charizard one. Yes, I've fallen into the majority here, but what can I say. I've always enjoyed Charizard, and to see the Pokemon make a return this way in the Fifth Gen. really is kind of awesome, though weird because of how the region is set up. (All new Pokemon and what-not.) Still, I like that Charizard.
The Blastoise one is another favorite, with the combination of blue on black. But the fact that the buttons are on the right put Charizard just a bit more ahead of Blastoise.