To properly answer this, you’ll have to run some numbers to understand how damage is calculated in Genshin.
So, Damage is equal to
(Base ATKxATK% buff$ + Flat ATK buff)
(Skill DMG multiplier)
(Elemental/Physical DMG + external buffs)
Assuming no crits.
So, we can run the numbers. Razor’s base ATK at lvl 90 is 234. A maxed out lvl 20 feather has 311 ATK. A maxed out lvl 90 prototype has 565 ATK and 27.6% ATK.
I’m just going to pretend flawless artifact substats exist. (What a joke). The highest possible ATK% on a substat is 5.8% per upgrade. Assuming every upgrade hits ATK%, maximum artifact substats would be 34.8 ATK%. And a bonus substat of 19 ATK on each non-ATK% artefact as well. And for the ATK% artefacts, a full 114 ATK.
So on a 4 pc perfect substat Gladiator set, with an 18% ATK%, and with all artifacts main stat being ATK%, capping at 46.6%, his total ATK at minimum would be 60888.
His skill damage multiplier for his normal attack at lvl 90 and at lvl 10 talent would be 181%.
So he would do 11020728 damage with a full gladiator set.
Now, we replace his gladiator set with 2 pale flames and 2 blood stained chivalry, and put physical DMG bonus on his goblet.
A lvl 90 Snow-tombed starsilver has 565 ATK and 34.5 Phy DMG bonus. A lvl 20 goblet has 58.3% phys DMG bonus. The two sets give a total of 100% phys DMG bonus.
So he would do 8808905683 damage with the phys DMG bonus oriented set.
So I think it’s safe to conclude that the phys DMG bonus set would do more damage, and you should go for that instead.
You should keep in mind that these numbers do not take into account elemental reactions, Crit DMG, Crit Rate, and skill/ult damage.
These numbers seem insanely huge, but that’s because they have perfect artefact RNG. Also, this doesn’t take into account enemy resistances. The higher level the enemy, the higher their resistance to damage, all forms of it. So the actual damage dealt to an enemy will be much, much less. These numbers would only really appear if you went to an AR1 player’s world and hit a lvl 1 slime in the face.