Lightning set or duke set

At this point is it even worth refarming the duke set for him? The only piece that I want to improve is the circlet (but then again I only need crit dmg and atk so it will be quite hard to get an improvement). Also does anyone know if atk or lightning orb is better if playing with Sunday and Robin?

At this point is it even worth refarming the duke set for him? The only piece that I want to improve is the circlet (but then again I only need crit dmg and atk so it will be quite hard to get an improvement). Also does anyone know if atk or lightning orb is better if playing with Sunday and Robin?