Best Staff Weapon

I;m sure Gravity+ or Pain+

Pain and Pain+ win for both imo

Definitely pain with dazzling effect upgrade and savage blow. Or if you don't have a pain one you can also use gravity with dazzling effect and drag back on a supporting unit. Still with savage blow on the unit.

It kinda depends on the healer imo. Most of what the others have mention is probably true. However as someone who uses a +Atk Lachesis as his main healer, I've enjoyed using Dazzling Fear+ on her with Savage Blow. Lachesis enjoys the high mt of Fear+ to increase her Physic+ heals or Recover+ if you have the fodder for that but Physic+ is the budget alternative as it's in her base kit. You could also run Gravity+ on Lachesis too but I do like the extra 2 mt of Fear+.