I know there are other Gospel singers and groups out there, but listening to Mahalia Jackson makes the rest of them sound like imitators. God gave her the voice, the faith, the presence, to take this to the whole world. We had an old Columbia (I think) Christmas record of hers, with a version of "Sweet Little Jesus Boy" that makes you want to cry when you hear it. I couldn't find a version of it on YouTube, unfortunately.
Here she is with Nat Cole, singing that old slave tune, "Steal Away" (with it's wonderful double meaning):
"In The Upper Room":
For Christmas, this is her rendition of "Go Tell It On The Mountain". In this song, you get the feeling that is exactly what she is doing, too, standing on the mountain and shouting out the news of the birth of the Savior.