Riding Horse: AC 10, 13 HP, 60' speed. +2 to hit, 2d4+3 damage. Warhorse: AC 11, 19 HP, 60' speed. +5 to hit, 2d6+4 damage, if it moves 20' before it attacks it has a DC 14 knockdown effect which also triggers a bonus action attack if it succeeds. So, the Warhorse is better in every way. Buff its AC with Barding and HP with the Aid spell and ... More @Wikipedia
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