To be honest, a lot depends on the execution of the piece, and on the acoustics of the place where it is sung. You can have a wonderful chant badly sung, or you can have a very simple one chanted beautifully. Again, you can have a chant sung beautifully in a room with lots of sound tiles (which pretty much kills the sound); or you can have simple chant in a large space with wonderful reverb, which gives it a mystical, timeless character.
All things being equal, I really like the traditional Easter Vigil Mass in the Roman rite, the whole thing–ordinary, propers, and all. It is so solemn, peaceful, joyful, and beautiful. You can get a nice recording of this from Clear Creek (I think it’s $15 or $20).
As for an individual piece, the following recording of the Salve Regina, Solemn Tone, pretty well fits your description I think:
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