What white mage materia should i be using?

[Exiled_Tonberry]

I think that White Mage has the tools to never run out of MP so I think the whole "SpS will make you run out of MP faster" is moot AND no need for piety ^^

My two cents ...

You can definitely run out of MP as a WHM if you're the type to DPS constantly while tossing in Cure IIIs and Medica IIs.

While I don't think it's necessary to really build into Piety, it's wrong to assume that your MP is infinite.