What if Nocturnal Sect...

[AlphaSonic]

It's not about the shields, it's about SCH tools compared to Noc AST.

SCH has better MP management
SCH DPS is better than Noc AST because it has better MP management and the fairy.
SCH has more reliable mitigation tools and easier to use. Supervirus lasts longer and its better than Disable. Sacred Soil is easier to use than Collective Unconscious. Eye for Eye is much more reliable than Bole. Even if Noc AST shields are a bit better than SCH. When Adlo crits it's godly, and it can even be deployed.
SCH Has better emergency cooldowns thanks to Lustrate and Indomitability
Noc AST has better DPS buffs than SCH... Well... SCH has Selene and her haste... So it evens out, and it can be better Selene if AST is unlucky with RNG.
Noc AST has more reliable healing tools than SCH thanks to Helios and Benefic II, well SCH has a fairy and Emergency Tactics (and in 8 man content there are high chances a WHM or Diu AST will take care of the main healing)
Noc AST can restore MP and TP to other allies, true, it can't be denied (if you are lucky)
SCH has the fairy, that gives free healing non dependant of MP and it has it's own abilities. Eos offers AoE Magic Damage mitigation, AoE regen and AoE extra healing potency. Selene offers a Silence, and AoE esuna and an AoE Haste.

You can't compare SCH with Noc AST. SCH is OP, really OP terribly OP.