For tools, Mending and Unbreaking III are mandatory for keeping gear alive long-term.
Efficiency V boosts mining and harvesting speed and pairs great with Haste beacons.
For weapons, Sharpness V is universal, but Smite V is best if you fight undead mobs a lot.
Protection IV for armor gives the best all-around defense unless you’re building a specialized suit.
Feather Falling IV on boots is underrated but can literally save your life.
Fortune III is essential for mining diamonds, emeralds, and ancient debris.
Thorns on armor reflects damage but wears your gear faster use it selectively.
Depth Strider and Respiration make underwater travel and combat much smoother.
Combining your enchantments on books first is usually more cost-efficient.