Elemental Goblets are really rare to get especially if you're looking for a specific element or attribute. What would be the best alternative for the missing piece of your artifacts? I introduce you to the ATK% Goblet artifact piece.
Here are the things you should consider if you're gonna use the ATK% Goblet Artifact piece.
1) Attribute Availability - If you are using a character with a specific element, an elemental goblet would be the best to use to improve the elemental damage of your character. Since ATK multiplies any source of damage, the ATK% goblet piece will definitely give you an additional damage output if you don't have an elemental goblet piece.
2) Available Sub-stats - in my own opinion, ATK% with good sub-stats is better than Elemental DMG Bonus with bad sub-stats. Having better sub-stats in the meantime will increase your damage output compared to the Elemental DMG Bonus with sub-stats that you don't need. The same goes with the Physical DMG Bonus; substituting with ATK% with better sub-stat is better.
Friendly Tip: Never expect to get an Elemental DMG Bonus based on the artifact set that you are hunting. For example: hunting Pyro DMG Bonus while hunting for a 4PC Crimson Witch artifact set. Imagine getting a Pyro DMG Bonus with bad sub-stat then you got Pyro DMG Bonus with better sub-stat in other artifact sets.
Having better stats will benefit your character in the long run.
What are your thoughts about this?