Often times I find myself appreciating music that was produced in Medieval and Catholic churches. And when it comes to chants, I would probably most enjoy Gregorian chants. There is something eerie yet calming when you listen to it. You also have the feeling that you are in large room with a very tall ceiling above you.
Gregorian chant developed mainly in western and central Europe during the 9th and 10th centuries, with later additions and redactions. Gregorian chant was traditionally sung by choir of men and boys in churches, or by men and women of religious orders in their chapels.