On all my tank/self heal classes I go with a DPS soldier. Archer is good, keeps good position. Warrior handles multiple mobs pretty well but stands in front of your position, so getting them where you want them can get frustrating. I recently started using a Sage on my captain. Does decent DPS and has debuffs. Can’t really go wrong with any of those. I think the most common choices are herbalist (you could challenge hard content) or archer (burn through skirms faster).
i would pick the sage. do not use the root skill, as you can easier move the enemies group in front of you, if the sage does not use it.
use the debuff options as % works better when scaled in later games.