I second Charles V of Spain, and I'm surprised so few people mention him in any capacity. He is basically the defining character of European conflict and politics of the time. Administering an empire where the "sun never sets" is an extraordinary feat, but couple that challenge with the brewing religious tensions that threatened the long-held order and you've got a deadly scenario, which he handled at the utmost best of his capacity as emperor. His wisdom to abdicate and split such a humongous political entity cannot be overlooked. In my eyes, his only lacking discipline would be military, although the numerous and embarrassing defeats he inflicted on his enemies could be said to count otherwise. All in all, in terms of EU4 monarch power system, I'd put him at 6-6-4.