My least fav provinces to take are the huge north eastern ones. Not just because of the undervelopment/slow growth or the mongols/tims as said earlier but i hate not being able to see everything in the provinces i own. So i spend alot of time finding the best places to put up watch towers. I dont know if anyone else has this problem lol. Seriously you should of seen the amount of watch towers in my Rus campaign lol. To come to think of it I dont think iv ever used a watch tower for there true purpose (if that is there true purpose?) to spy on enemy lands. Only my own.