Usually Rein, Cecilia, Xander, Eldi, since Eldi and Rein are using the during combat buffs while both Cec and Xander have hone Cav. I would argue that having Rein in front makes more sense because if you put Cecilia in front people are gonna realize that's a horse emblem team and plenty of people run Rein by himself. But perhaps Xander might be best.