Can't figure out which healer class to pick

I want to create an alt character, don't want to play hpala because my main char is a paladin (ret pala main but still, i wanna switch to a different class for my alt)

I am struggling to pick between Shaman and Priest. Was considering druid but I was told that Shamans are the best, and Priests will be picked for mostly their disco talent. Can anyone shed some light into this so my choice gets easier? I'm willing to spend 100% of my next wow playtime on the character I start next so I'd really appreciate some advice. Thank you!

healing tier list is pal>priest>shaman>druid

do with that what you will

Honestly a balanced raid will want one of each so it doesnt really matter. The playstyles are quite different though. Paladins are heal bombers, druids are blanket healers. Holy Priest / Shaman is somewhere in the middle and disco is a special utility case because it makes other healers job way easier. You can also look at offspec options for your MS heal, druid can obviously has 2 dps offspecs and a tank offspec, pala gets ret / prot. Shaman is probably the weakest in this regard since you get ele/enhancement which is not that high in demand.

As a Priest you'd be more or less expected to be Disco 24/7, with off-spec being either Shadow or rarely used Holy.
Disc Priests can get bit dull in 25 man raids, bubble here, bubble there, bubble everywhere. Though you're quite free to do other stuff when you don't have to stand still and cast that much.
With a Shadow OS, you'd at least have desired DPS spec, something Shamans kind of don't have.

Shamans can be versatile healers, and there's fun to be had. Should get raid spots easily too, as it's more common to have two Shamans than any other healer specs/classes.
You're expected to solely be Resto, and honestly, being able to play Shaman DPS is something of a rare treat. I've always seen it something as "You've done well as a Resto and established yourself in the core raiding team, now have your fun as a DPS." Other healing classes/specs kind of lack this as they have more meta/viable DPS/Tank specs.

I'd recommend watching 10 and 25 man HC raid videos and see what matches what you want to do as a Healer.

Personally I think Disco Rocks bro, I main one

but in my general experience i find that most Pugs like HolyP and Rshamy as healing combo

this tip helps me so hard thanks

I am currently doing a druid and I do not like the healing. it feels like you are always doing max output heals no matter what is actually happening. I prefer to heal on my Shammy.