Get Kirk Franklin's Christmas Album.
I totally agree. Kirk's album is a good selection of youth choir oriented Christmas songs.
"Emmanuel" by Norman Hutchins is DEFINITELY a winner.
"The King Has Come" by James Hall, "Joy to the World" by The Colorado Mass Choir, "Born to Die" by Hezekiah Walker (from the "Real Meaning of Christmas").
Also it may be good to invest in these Christams albums:
James Hall Christmas
The Real Meaning of Christams (Vol I, II, III)
Gary Mayes "The N.E. Xperience, Vol II"
Donald Lawrence "Hello Christmas"
Norman Hutchins "Emmanuel"