Question about %increase physical dmg and %increase elemental dmg with attack.

Hi, I'm trying to craft my own endgame GG crossbow, I'm using shockburst round for killing rares and bosses, I built around crit and already fractured a +5% crit base. But I'm not really sure which mod will scale dmg the best for shockburst round. I tested on POB, the mods for maximum physical dmg for prefixes like:
%increase physical Damage
Adds # to # Physical Damage
Adds # to # Lightning Damage
seems to yield higher dmg than
Adds # to # Physical Damage
Adds # to # Lightning Damage
#% increased Elemental Damage with Attacks
Given all the mods are T1, what do you guys think? Just want to make sure.



Also for socket runes, 50% increase atk dmg against rare or unique enemies is the best for boss right?

I m crit Xbow build with Galva/Shock + Plasma. First Approach build with %45crit chance (%100 on full hp targets) and 1280 crit bonus (1360 on full hp targets).

% phys
added phys
accuracy+phys (lucky roll) in here you might go %ele damage
Crit chance
Crit Bonus
+7 Projectile

Use Crit Bonus Runes on weapon as well.

This is best for crit build. Good luck. Don't worry for shockburst rounds if you have kind of Xbow. Your Plasma Burst probably going to one shot or leave boss at %20 hp.

GL