Deirdre

she's already quite slow, so unless you have some way to salvage her speed, try +atk/-spd

+Atk is wayyy better than +HP for her, and her def and spd are on the same level of usefulness to her as they're both very low. So I would go with +Atk -Spd

I'd go with +HP - DEF.

Deirdre has a superbane in speed which makes doubling opponents even harder, on top of making her even more fragile towards distant counter opponents, bow/dagger users and, most importantly, dragons which she is designed to counter.

It also undermines her default skillset that's designed to mitigate her otherwise average speed whereas her Defense is already too low to salvage. The extra HP will make her more effective at tanking magic damage also and makes up for the lower defense.

Go for +atk, that way you can secure OHKO to dragons, just give her res ploy in SS and deathblow in the A slot.

You dont need a lot of spd thats why she has QR.