As much as I want to play as the 13 Colonies (yeah i know they are in the tutorial, but have they been confirmed in the Campaign at the start?) , honestly I will probably start as Spain. It is the safest starting position in the map and, there should be more than enough resources in the Iberian Pensula to exploit. And it has been mentioned before but most of Colonial Spain is in South America and fairly isolated. IMO, (depending on the unit roster) Spain is a great and for the most part, safe, first pick.