Recommended Chestplate Enchantments
Protection IV
Best all-round damage reduction. Pick ONE protection type - Protection, Blast, Fire and Projectile Protection are mutually exclusive.
Unbreaking III
Chestplate durability lasts about 3x longer.
Mending I
XP repairs the chestplate - effectively immortal combined with Unbreaking.
Thorns III
Optional: reflects damage to attackers, but drains durability faster.
FAQ
What are the best chestplate enchantments?
Protection IV, Unbreaking III and Mending. Thorns III is optional. The chestplate has no piece-specific enchantments, so this is the full god set.
Is the chestplate worth enchanting first?
Yes - it is the simplest piece (fewest enchantments) and gives the biggest durability pool of any armor piece, so the Protection IV investment pays off the most.
Protection or Fire Protection on a chestplate?
Protection IV for general play. Fire Protection IV only wins if you spend a lot of time in the Nether or near lava - and it is mutually exclusive with Protection.