The 24/15 one is probably your best bet, but if you're going without a shield, 18/24 is pretty insane on a courser, even an arabian warhorse if you're the type to follow melee crowds and effectively offer bump support with surgeon-level dexterity. No room for Ironflesh, and you only get 3 athletics, but 8 riding is a blast. The stats look pathetic, but its honestly very effective.
6 PS
8 Riding
3 Athletics