Mine was Anima because her "fayth" was the mother of Seymour and she perfectly reflects the sorrow and sacrifice she did for her son only for him to end up evil
Anima. Incredibly useful and well developed backstory. Easy win. The rest are fairly anonymous
Magus Sisters are second for being inhumanly powerful and I liked their playstyle of recommending actions. I love Shiva's artstyle, so she's up there, and Bahamut is also awesome.