Is it holy or disc? for me i prefer Holy and i can’t play discipline well.
Then for you, the answer is “Holy”.
Holy can do anything. Tank healing, spot healing, aoe healing at anytime. Best raid healer if you don’t trust co-healers.
Disc is a for soften up/handling mechanic. A burst healer for handling all tough mechanics. Need to trust other healers to spot heal while ramping up the burst also have high mana cost for tank healing. Better for Progression raid.
Then go holy.
I go holy for pve, disc for pvp.
disc is built for 20 man raids, either will be viable though
In the first week, if your guild is bringing a bunch of people to Normal/Heroic, Holy will likely out-perform Discipline. Discipline excels at healing 15-20 targets at a time, but they need a TON of haste and mana to heal any more than that, so they cap out quickly. Holy is a very good spot healer with strong cooldowns that will hit the whole raid, so their healing will be effective regardless of raid size.
In Mythics, where the raid is always 20 players, Discipline is extremely strong, and with access to Spirit Shell this xpac, even stronger.