I wouldn't say that I am too attached to any of them other than "Leah" and this is just because that is the only vision that grants any character the opportunity to be a healer.

Your crew has a dedicated healer all the time anyway but if that person ever falls in battle you have a real problem Plus, the highest powered healing spell, which will be necessary against big bosses, consumes so much MP that you can only use it a couple of times before that toon is out of MP>