Portugal. Split territories, neighbours to two potential superpowers in the Muslim Moors who can attack them without fear of Papal condemnation, and the Spanish who are in easy striking position of both Portugal and Naverre which they could hit at the same time easy.

To survive I'm betting that you would need to either buddy up with one against the other, which opens more problems. Do side with the slightly apparently more powerful Moors (open to debate that one) or the same faith Spanish who you can't attack without excommunication? If Portugal can survive the early stages though it'd be a good position, close to the New World, great trading position to both the Med and the north and far from the Pope and any marauding bands of super-calvary factions coming from the east to kill and plunder indiscriminately. But then, what's the chances of the latter happening....