I can't recommend much but I'll give you a comparison. I was in a party earlier with someone the same level as myself. He's using a full armor set, while I was using a full protector set. He's a lightning spear, I'm a lightning bow.
The Toaist did me about 200+ damage with their fire blast attacks and about 79 to 9+ damage with fireballs. The guy wearning armor was taking more damage as compared to me. He was getting 350+ from the fire blast attacks and about 135 to 160 damage from the fireballs. I'm sure it will be significantly reduced with garment but Taoists aren't the only thing in that area.
I've never been a pure STR player, so I am not sure if I can really answer the question. PvP damage depends on what kind of character you're fighting against. A pure STR character will deal more physical damage and you'll be better protected by armor. A pure INT character will deal more magic damage so you're better protected with Garment.
I couldn't decide which is better so I stayed with Protector
