Well, Gjallarhorn would be the exception. It's quality perk is that it gets way more powerful. Ice Breakers quality perk is that it regenerates ammo. Thorn causes dot. Patience and time makes you invisible. Aclyophage symbiote gives you an extra golden gun shot. And many more that don't increase damage. These are all fun to use (not as much fun to be killed by). Damage output does not equal fun in all cases, except Gjallarhorn. Damage does not equal quality.