Honestly, play whatever you’re interested in, make a class trial and experiment a bit.
Don’t let people saying one spec is bad, or good but difficult, discourage you from trying a new class and deciding for yourself whether you like it or not.
Disc is great and has a somewhat unique mechanic of healing.
Hpriest is a great entrypoint for healing since it has very intuitive healing mechanics.
Druid is one of my favorite classes in the entire game and restodruid always has great potential.
Paladin, being effectively a melee healer, also has some sort of uniqueness to it that people find enticing. Its also got great utility spells with Freedom, BoP and auramastery.
Shaman has an incredibly fun playstyle as well as spirit link totem, which is one of the strongest raidcds, as well as works through necrotic. Plus it can turn into a ghostwolf which is pretty swell.
And Monk can probably convert his mana into hps five times as quickly as any other healer can, I’ve never died having a mistweaver in my group, unless it was a oneshot or the monk went oom.
They’re all great in their own way and all of them are at the very least playable.
I don’t recommend choosing based on recommendations or whatever’s currently the fotm. I recommend finding whatever you enjoy playing. Because unless your goal is to play as effectively as possible, your goal should always be to have as much fun as possible. And playing a class you don’t like won’t end up in said thing.
That being said
Disc > Hpala > RShaman >= MW Monk > Hpriest > Rdruid
That’s regarding my personal opinion regarding how much fun the respective spec is, no matter how strong or weak they’re currently considered as.
Purely from a raidperspective as well, MW Monk and Rdruid would climb a fair bit while disc and shaman would drop a fair bit for m+.