Late to the party on this topic but I am a big fan of Christmas music about four or five years ago I came across two lists online called The 100 Greatest Traditional Christmas Songs & The 100 Greatest Contemporary Christmas Songs.
I have slowly been trying to acquire all these songs starting with the Traditional and now have all but around 20 stored on my computer. Most of these are from around 1940 to 1969 with names like Bing, Dean, Frank, Nat King Cole, Perry Como, Ella Fitsgerald etc.. there only three songs over 1969 two by Johnny Mathis It's The Most Wonderful Time of the Year (1986), It's Beginning To Look a Lot Like Christmas (1986), When My Heart Finds Christmas (1993) by Harry Connick, Jr.
According to this list here is the Top 5 "Traditional" Christmas Songs.
1. White Christmas (1942, 1947) Bing Crosby
2. The Christmas Song (1946, 1953, 1961) - Nat King Cole
3. Rudolph The Red-Nosed Reindeer (1949, 1957) - Gene Autry
4. Sleigh Ride (1950, 1959) - Leroy Anderson
5. A Holly Jolly Christmas (1964) - Burl Ives
The "Contemporary" list still has some songs from the 50's & 60's at the top of the list mostly from the Rock & Roll era names like Elvis, The Drifters, Temptations, The Ronettes, Chuck Berry, Bobby Helms, Beach Boys & Brenda Lee.
Most are from the 70's & 80's and a few 90's songs like All I Want For Christmas is You (1994) by Mariah Carey & one or two from Trans-Siberian Orchestra. I only have around 30 of these stored.
Here are the Top 5 "Contemporary" Songs.
1. White Christmas (1954) - The Drifters
2. Rockin' Around the Christmas Tree (1958) - Brenda Lee
3. Christmas (Baby Please Come Home) (1963) - Darlene Love
4. Santa Claus Is Coming To Town (1975, rel. 1981) - Bruce Springsteen
5. Do They Know It's Christmas? (1984) - Band Aid
I'm a big country music fan as well so here are a few original songs I like.
Country Christmas by Loretta Lynn
Hard Candy Christmas (1982) by Dolly Parton
Meet Me Under the Mistletoe (1989) by Randy Travis
Til Santa's Gone (Milk and Cookies) (1995) by Clint Black