EnchantView Mod shows what the enchantment table will give you BEFORE you click on the enchantment, so you don’t find yourself in the situation where you’ve wasted 30 levels on nothing but Unbreaking III. Just move your mouse over the enchantment box and a little box will pop up telling you what item you will get if you click it.
Download link: EnchantView Mod 1.8/1.7.10