The Grunts appears in most locations with scary atmosphere but not the Brutes

[Tommyboypsp]

I disagree with your statement that the prison is more scary than the choir. A place where people are locked up vs. a place where people are tortured. I think I am more scared of the choir.
Even if you're purely talking about atmosphere and music, I still think the choir is scary. It looks dark despite the fact that you don't need a lantern, and the music from the main menu plays there. Also the monsters spawn more dangerously, as in, you're more out in the open which for me and I think more people is scarier than when a monster spawn when you're near a room to hide in.

I'm not saying the prison or storage aren't scary, I just think the choir is also scary.