There are so many options during the late 15th and early 16th century to go with.
Arthur, Prince of Wales, Henry, Earl of Cornwall for England. Even Edward V of England.
For France, Charles Orlando born in 1492. Francis III of Brittany is another.
And my beloved Trastamaras and Avis got screwed really hard. Alfonso, Prince of Portugal. Juan, Prince of Asturias, Miguel da Paz. And even if she's not a man, I would say Isabella of Aragon could have been a great ruler if she had not become such a tragic figure.