I started playing this a few weeks ago, and I have no idea who I should focus on. I have orlandeau and firion at 6 stars. My other units that can go to 6 stars are :
Chizuru
Agrias
Setzer
Ashe
Goken
Ayaka
Lucca
Warrior of Light
Gaffgarion
Snow
Nine
Sozhe
Grace
Amelia
Rasler
Werei
Xon
Veritas...