PoH is just a dead ability because a single cast of Flash Heal w/ Trail of Light and Binding Heals does 50%+ more healing.
Most of the builds ignore CoH because they want to treat Holy like a Flash Heal jack hammer to solve most of your problems.
CoH in itself is not a bad ability, but with the loss of the S3 DF tier set bonus you’re not getting free Renews and stacks of Healing Chorus passively to always hit 20+ stacks every 9 seconds.
If you have 3+ Renews rolling out you can hit 20 stacks every 9s and CoH does a reasonable amount of damage per cast.
I posted some data here on CoH:
If I didn’t have Archon Halo and CoH giving 40+ mil free healing then I would have to instead cast twice as many Flash Heals in a dungeon to do the same amount of overall healing. That’s easily 150+ Flash Heal casts.
So to answer your question: CoH is viable and strong, especially since it got a +30% buff recently, but you have to manually roll out Renews to always hit 15+ stacks of Healing Chorus to maximize it.
if you maximize Halo, CoH, and other abilities then long-term you’ll be a lot more mana efficient in dungeons and not ooming constantly.
My build: