Can heal ? Cleric 2.
Can buff ? The Priest’s and Pardoner’s buffs are available from shops. So you are left with other buffer-ish classes like Krivis, Paladin, Miko, Dievdirbys…
Can take damages ? Surviving isn’t really an issue for Clerics in general, but Cleric 2 gives you a good Safety Zone, Dievdirbys gives you invincibility, Bokor has Mackangal, PD has Healing Factor…
Can deal damages ? Your PD in your build will cover most of that already. And then a lot/most cleric classes can deal decent to good damages.
Priest still has useful skills (Res, Rev, Mass Heal…) but buffs-wise yes, they’re more of a self-buffer than party-buffer now because of the shops.
Aspergillum is also a self-buff, not a party buff.
You seem to want to be able to be the main support in difficult-ish PvE contents, bring utility to the party, while still being able to stand on your own, right ?
Here’s the build that came to my mind right away: Cleric 2 - Dievdirbys 3 - Miko - PD 2/3.
Cleric 2 is the must-have and obvious. Dievdirbys will bring you protection/damages mitigation, debuffs, utility to your party. Miko will make your Diev shine and will also bring you extra damages and Kagura buff.
Full SPR because your Owls damages will scale with your SPR while working on your weapon will increase your MATK so you don’t need INT.
For support, you also have Paladin.
You can decide to keep PD and Cleric 2 for the support (maybe throw in a Priest 1/2 for extra support) and then you can add Sadhu or Bokor, both would bring great damages.
Priest 3-Chaplain isn’t that much of a support anymore imo. The first two ranks of Priest are mostly for support, yes, but Priest 3+Chaplain is when you want the support but also the independence of the solo AAer.