I'm afraid I would live a lifetime of regret by picking an album, while forgetting about another gem.
If I had to narrow it down, I would probably say Bert Kaempfert's Christmas Wonderland or Christmas Favorites By The Hollyridge Strings.
Now consider all the classic crooners left out in the cold. I shudder at the thought!
I too don't think I would be able to make a final selection.