The reference to Pat a Pan, a Christmas song, recalls to my mind that, with so many Christmas carols and songs being historic or traditional, there are many superb versions out there. Burl Ives comes to mind - and Judy Collins as well - in this category both generally and, with Burl Ives, Christmas.
One of my "Hallmark" Christmas CD's (which I think most of the folks here are old enough to remember ) has the most memorable version of "What Child is This" I have ever heard, but I regretfully don't remember the singer and it is packed away. Also, Harry Belafonte is on one of those CD's with beautiful versions of several traditional carols.