critter : zerk slayer ( but slayer tank less than zerk with same stuff BUT you can win all shrine with slayer if you perma invincibility , you need 95% CD and no one can hit you but you cant hit too ^^ )
Caster : mage archer ( depend what you need , killer => archer , medium killer but more helpfull for castle => mage )
Hybrid : you got choice , Swash full buff with shrine parts is amazing , summoner uge dmg in Aoe's and still good crit with only pants shrine .
Elem you need uber stuff , hunter is very good but for tank and debuff ( mage and archer are better on pvp ) , ranger hum i think you need uber stuff + shrine parts and could be cool on crit + HH skill , orbiter useless , knight = for tank only