Important: Everything I recommend here is with in-game resources, NEVER SPEND GEMS on any of the shops unless you are a spender or trying to min-max.
Only when needed
The new yellow stones are a must-buy and will impact what other items you can get since they cost 10,000.
I personally skip the character and pet summons unless I have extra currency, since the souls you get are not that much.
I clear the whole shop BUT mystic stones. If you have spare currency before the weekly reset, get them.
When you are high rank enough in PVP, you can get either the gold souls or reroll tickets for gear.
The reroll system is not that good, so I would recommend souls over those.
This shop changes a lot depending how you play the game. I personally buy:
I buy gold souls on the mileage shop since it’s cheaper to convert them that way.
Similar to the soul shop, this changes a lot depending on what YOU want. I personally buy: