What is Reddit's opinion of Christmas Now Is Drawing Near: Engl Folk Carols?
From 3.5 billion Reddit comments

By popularity on Reddit, this product is:

1 review of this product found across Reddit:

If they love classical music, Handel's Messiah and Bach's Christmas Oratorio are great. The Messiah is a LOT more famous and easily recognizable, so if they don't know too much about classical music it might be a safer bet than the Bach.

A strange and little known personal favorite of mine is Sneak's Noyse: Christmas Now Is Drawing Near. It is a collection of OLD (medieval and renaissance) English folk carols done with period instruments and singing style.

If they like jazz, and if you can find it, they might like one of the Swingle Singers holiday albums. I grew up with these, they are great fun to listen to. Also, no holiday is complete without Vince Guaruldi Trio: Charlie Brown Christmas. So, so good!

Another strange and wonderful album I grew up with is Pete Seeger's Christmas album. You have to love the banjo for this one, though!

Hopefully some of these will make your parents happy :-) Good luck, and I bet I can come up with more if you like!

EDIT: we also have some great scattered tracks of various big band artists doing Christmas stuff, but it looks like most of it is out of print. If your folks like big band jazz, you might try looking for tracks from this album, or just hunt around for tracks by Benny Goodman, Tommy Dorsey, Glen Miller, etc.

(BTW -- Sorry about the Amazon links! Not sure where you get your music, they're just so you can see the album covers.)