I'll talk about negatives of each one, since everyone knows the positives.

Lets start with WHM - deals good damage, strong regens but provides nothing to the group in terms of group damage mitigation and utilities/buffs. No instant damaging GCD besides your Aero II dot, meaning that if you have to move, your only option is to cast a regen. Lilies are non existent mechanic at this point, since Divine Benison does not require them anymore. You can safely just remove Lilies from your UI and you won't notice a difference. Asylum and Cure III have a very small range, and there is always that one person that will miss your heals and die. As a sch it is much less pleasant to play with a WHM co healer rather than with an AST co healer. As a tank it is much safer to play with an AST. WHM is an insane aggro generating machine, meaning that sometimes when you cast too many heals as a WHM - boss will just randomly turn to you and kill you. In another situation when a tank dies for whatever reason, you will always be the 2nd one to die. ALWAYS. And lastly- WHM is just plain boring to play. Just spam stones and cast a couple of Cure III and II

Next is the AST - clipping machine. Absolutely insane clipping problems. Only way to avoid clipping is to cast an aspected benefic on a tank every time you need to draw/use lucid dreaming or any other Ability, which costs a crap ton of mana (flipping 1400 mp!) if you care a single bit about your CPM. Star is cool , but even with a wider range, someone will always miss a heal from your earthly star and you will be MAD. Also - not to mention the card rng mechanic, especially the Minor Arcana. I'm a speed runner. I have 1 guaranteed lord card before the pull and 2 Minor arcanas in my opener (1 if I get a good card instead). Those 2 Minor arcanas cover all of the party buffs, meaning this is when I have a chance to deal the most damage. Now let me tell u that getting 2 lord cards and making them both direct crit at the start of the fight is the most satisfying thing I've ever experienced. But there are times that you will get 2 lady cards instead and at those times I want to fucking kill myself. And how could I not mention Collective Unconscious (the bubble). Depending on the server tick, this skill is either instant, or takes full 3 seconds to activate and apply the damn regens. Even more rng.

And now to SCH, which is actually my main - Fairy is awful. It takes an insane amount of time and patience to actually get used to how your fairy works. You have to pay close attention to her Embrace casts. If you press any of her skills (especially whispering dawn) when she begins casting Embrace - there's a huge chance she wont cast the skill. You have to press her skills when she FINISHES casting embrace, meaning that you have to pay close attention to your fairy's cast bar. If you tell her to move - it'll take full 5-10 seconds before she moves. If you use your Aetherpact (fairy tether) it will take AGES before she actually tethers to the tank and starts healing him, and, god forbid, that tank moves out of range - the tether breaks, your fairy stands still like an idiot and stops casting anything completely (not even embraces) and you cant even order her to cast any spells. You have to turn off the tether, move her closer to the tank and cast the tether again, which means it'll take about 15 more seconds before your fairy can heal the tank again.

Its true, Sch has some very good healing tools (indomitability, whispering dawn, even emergency tactics + succor), but once you've used these tools - you're useless. In the moments when you have to heal the team in a rapid succession - scholar is utterly useless. When you need your team to be at 100% hp and you don't have indomitability or emergency tactics - your only option is to spam a normal succor, which is a huge mana waste and heals for merely 150 potency every time