If you have the Necromage perk, what is the highest level Turn Undead spell you really need?

Define "need." With Necromage, Guardian circle hits anything below the level 40 Deathlords (the only really tough ones), and Bane of the Undead hits everything. By the time you have those spells, and Necromage, you are probably facing 60% Deathlords in dungeons, so any lower spell isn't very worthwhile.