There are as mant different ratings of ammo as there are different types of ammo. None have all the right answers. It pretty much comes down to kinetic energy and how much of that energy is delivered to the target. Large caliber, heavy projectiles have the advantage. Wadcutters and large hollowpoints are more likely to stay in the target rather than passing all the way through and therefore will deliver all of their energy to the target, giving them and even larger advantage.
Do they still make Glasers? Frangible ammo with a really high muzzle energy that shattered on impact and delivered a ton of energy to the target and was a good home defense round because it would not go through the target and hit someone -thing behind it.