I dabble with all healers, though WHM and SGE are my mains. Main things I'd want are:

General/Misc.
  • Adjustments made to shield overrides to prioritize stronger shields winning out. {Eukrasian Diagnosis} should not be a blanket override to Galvanize, especially when it's from a crit Adloqium cast. Potentially including "wasted" casts refreshing the shield timer either partially or wholly.
White Mage
  • Rework Freecure into a trait that gives the job's other heals a chance to proc it, instead of just Cure. Something that makes it worth using outside of coils.
  • A new lily option for regen to complete the trifecta.
Scholar
  • Energy Drain to be reworked away from a damage dealing move (X or damage design), either back to an MP regen or a Fairy gauge boost so it still acts as an aetherflow dumping move.
  • The ability to use Eos as a movement option, similar to BLM's {Between the Lines}.
  • Eos automatically teleporting to your side if you accidentally leave her on Place mode in a boss fight.
Astrologian
  • Cards to be reworked slightly so they're more distinct. As it stands currently, there are really only effectively 2 cards, melee buff and ranged buff, and very little reason to give any to tanks (outside of DRK opener) or healers.
  • Give {Undraw} a reason to exist. Even if it's just eating a card to get MP back.
  • A new ability that ties into the fortune reading and preplanning side of AST. Maybe a shield that only becomes active after 5s.
  • {Minor Arcana}'s cooldown being visible even when holding a card.
Sage
  • More combos with {Eukrasia}. Like {Eukrasian Dykrasia/Toxicon} as an aoe DoT, or {Eukrasian Phlegma} giving your patient a shield instead of a heal.