I have seen people trading an exiled piece with an enchantment plus a lot of crowns for some clean ones.
Hard enchantment would be the best because it gives a little bit more defense than hard Iron Armor and provides the extra knockback which is somewhat useful. OTher good enchantments would be the strong enchantment for extra magic damage and forceful enchantment for even more knockback.
Hard or strong are still the enchantments to go for in terms of Exiled pieces.