One account with Amon alone and the other with Amon + another SSR.
Amon is great alone, even with other SR kami but only until certain point because when you reach level 30, you will notice that you need someone else as strong as her to progress through main/SP missions. She has decent buffs against boss battles, but nothing that you could potentially use to fight monsters, well she has one skill but as I mentioned before it works best with boss fights
Stats at level 40: