Best Way to Enchant?
If it’s a weapon/off-hand, use forced enchanting to force the hardest or rarest enchantments on the crafted item. Then use the enchantment table to finish it off by replacing the last enchantment.
If it’s anything else, craft using items with the same-enchanted material(s) for the crafting cost will have enchant rates approach and even reach 100%.
The more you add to the pool, be it different enchantments or non-enchanted items, the worse the rates are going to become.
Can’t use enchantment table to enchant all equipment anymore so crafting is your best option, assuming you want quad enchanted gear.