I'm in a little bit of a predicament here. Right now I have 3 rainbow fairies and I'm going to one more for this month and a couple more from next month and events. My question is who should I use them on? The units I want to raise skills would be Spica, Sybilla, Nanaly, and Mikoto. But between those four, Spica or Sybilla would be my top priority for skill AW. Any thoughts?