What the letters mean
The rank is for staying alive in Story Mode while five babies still need care. Detective is high because fake babies and strangers are how runs fail. Exorcist is high because the flash is the tool the tutorial tells you to use, with the caveat that its price is listed two different ways. Escape Mode may not use every childcare ability.
S tier
Player decision Save for this after Babysitter if you already lose babies to impostors. It is the strongest information tool in the coin shop.
Player decision Buy it when darkness and a dead camera are why you fail, and only at the price your own shop is showing.
A tier
Player decision Buy this first if chores, not identification, are the bottleneck.
Player decision Take it after you can already spot impostors and still die to stains and your own contamination.
B tier
Player decision Equip it on days you expect to finish, when you are saving for Detective or Bodyguard.
C tier
Player decision Add it after you own a class you actually play. Do not make it your only purchase.
Player decision Buy it for outfits after the coin classes you need, not as a survival upgrade.