Huh weird. I just finished my Pure priest run, and well into my Bleak Waelker run. Having lots of fun on both, but I do play with mods that give the priest extra casts, and buff some of their spells(Like crowns for the faithful.
Although Berath is certainly a different coloured horse than Eothas I imagine them playing the same. Litany for the spirit/Minor Avatar, throw buffs, and then throw heals as needed. I don't know about the Dawnstars, but the Pallid Knight and Usher summons were incredibly underwhelming since they can't penetrate anything on harder difficulties.
Bleak Waelker(Bleak Walker/Wael Priest) is a lot more active, but has less cool abilities. I imagine any templar to be a Tank/Support, but not utterly impossible to kill like Heralds are. Also I tend to run with a pure priest just so I can have someone pop the really good buffs and debuffs while the MC focuses on healing.