How you chose your healing job.

[Atoli]

I didn't really "pick" AST, AST picked me
It's more akin to falling in love than a concious decision for me xD

I always, in all games, enjoyed support (as in various buffs and some heals) more than pure healing.
Because of that, WHM was okay-ish to me but boring, as all I was doing was healing and DPSing, the Protect cast at the start of the dungeon not really counting.
SCH never sat well with me; mainly because the last remaining part I enjoy about healers who can't support is the actual healing - which is mostly done by the fairy on SCH.
Also found the DoTs annoying to place, the shields less speaking to me than WHM's regen, etc.

Then AST was released, and everything was perfect
I have ALL the support buffs, decent heals, regen, even shields if I want them sometimes. Also helps that the skill animations are just BEAUTIFUL.
As time passed, I also embraced the lore of the class on a deep level, so now I won't even rage anymore when I get 6 spears in a row
Because..it's fate :3

[Vele]

I nearly always play a healer on MMOs so when I was looking into FFXIV and asking friends the difference between sch and whm, they were saying sch was better because they had shields, a fairy to help heal, a really op single target "oh crap" button you could use up to 3 times per minute (back then lustrate was a flat 25% hp recovery, even in cleric stance), and if you were good enough, you could put out some decent dps on top of everything else.

It worked out for me because I'm a big fan of classes that use books as their weapons, and in many mmos those are usually reserved for the dark sorcerer/necromancer types. Summoners fit that role since they're like poison mages here, but I was very pleased to know you could be a healer and still have a book.

I leveled whm later though, and while sch was still my preference, I no longer believed one was better than the other in every situation, and ideally you wanted both in full parties.

I sort of like ast, but I am not a fan of RNG. I pretty much only play it for funsies in expert roulette or 24 man raids if I am going with a friend, so I can give them all the cards.