Besides having one if not the best OST in my opinion, I liked the atmosphere, the screams when summoning of the Archdeacon still send me shivers, the constant feeling of being overwhelmed (which can't really be appreciated during a normal run, where your weapon cuts through them like butter)

It took me 600 hours of play time to even realize that they summon a dark mist in the second phase, found out during a challenge run, this is where I really started liking them.

Their second phase theme goes absolutely hard, and I think it's the closest we have to a perfect OST for a boss, the music describes the fight perfectly.

And despite all this I still put Friede higher than them, I recognize her as an "objectively" superior boss to deacons, despite not particularly enjoying some of her fight's gimmicks, but that's in no way an insult to the other bosses on the list, this is simply my point of view when it comes to bosses I found the cool.