Hey, there are two threads on Costume Domitia vs. ____ that you might find interesting:
I realize neither of those is exactly the situation you’re in here. But I think you’ll find them useful anyway, as they discuss the pros / cons of each choice. Personally, in your situation, I’d lean towards Domitia (assuming you have a level 5 or greater mana troop, which will eliminating most of the mana speed advantage Sartana has against her).
You don’t appear to have Seshat, so the dispel will be useful - C. Domitia has a lot of versatility since she can dispel / cleanse as needed. When C. Sonya joined my roster she saw a huge boost in usage for that reason. I see you have C. Sonya, so you probably know what I mean.
Without Sartana costume, the statistical edge goes to C. Domitia.
*Damage numbers from Guvnor’s thread.
That said, check on your emblem situation. If one is in line for emblems, that could tip the scales.