Hallelujah is one of those songs that is special no matter who is performing it. Originally written and recorded by Leonard Cohen, the song gained popularity with later recordings by John Cale and Jeff Buckley.
The song has since been covered by over 300 other artists, and has been featured in countless mournful scenes in movies and TV shows (Shrek and The West Wing come to mind first for me.)
This version by Pentatonix was released on their Christmas album, but I listen to it year round. Do you have a favorite version?