In patch 3.3 Enchant Chest - Major Spirit is the best enchant for shadow priests, so it has to have same value as Enchant Chest - Powerful Stats (difference between those two is minimal).
Also Enchant Weapon - Black Magic is supposed to be a better enchant than Enchant Weapon - Mighty Spellpower, but that's in theory. In practice both of them probably have the same value, due to RNG, so for 1H weapon they must have the same value for shadow priests.