Honestly Svarog is the best option. She is the most core fire hime who is great in pretty much all circumstances. Followed by Mars. Amaterasu in some situations may not be that great. She is considered core mainly because of the B frame debuff. However aside from Wind Rags (Catastrophes), there will be more non-debuff friendly content if you wish to throw fire at them.
Mars is still more useful because her ability is an elemental resist down and also acts as a Mini VoF. Against Wind Rags or any wind opponent, it becomes a 6.5x nuke.
If you had Konohana Sakuya (R) or Hephaestus (SR), it would make it much easier. I’d suggest going for either Mars or Svarog. If you’re going to invest in this Miracle Ticket and the next, make sure you grab these 2 first. You can go for Svarog now for the raw power in case you have the Mats to AW her while hoping to get Sakuya or Heph for debuffs for whenever you roll with Jewels.