Well technically it's only better for you than defense once you're to the point where enemies are doing more than 100hp damage to you in one hit.
If they do less than 100, def is better:
For example, with 10 def and 10 prot, lets say you get hit for 50 damage:
(50dmg - 10def) = 40 dmg - (40dmg)*10prot = 36 dmg
In this case, 10 def gives you a 20% reduction in damage whereas 10 protection gives you a 2.5% reduction in damage.
Def is most important for beginners...once you get up there, prot is more important. Of course...the best way to do it is to not get hit at all.
