I was intrigued to google for further information. It seems the Darke version was voted the best carol of all time in 2008 by a panel of choral arrangers and choral conductors. Additonally, there are quite a few more than three settings of the poem. Herewith the Wikipedia paragraph on that point:

"The text of this Christmas poem has been set to music many times, the most famous settings being composed by Gustav Holst and Harold Edwin Darke in the early 20th century. There is another settingâ€"less well knownâ€"from the same era, by Thomas B. Strong. Benjamin Britten includes a setting for chorus in his work "A Boy Was Born". Eric Thiman wrote a setting for solo voice and piano. More recently Bob Chilcott, at one time a member of The King's Singers, wrote a choral setting entitled "Mid-winter". Another recent setting is that by a Canadian, Robert C L Watson. The Holst version has been recorded by a number of popular recording artists, including Bert Jansch, Julie Andrews in 1982, Allison Crowe in 2004, Maire Brennan in 2005 and Sarah McLachlan in 2006, as well as by many choirs including the Robert Shaw Chorale and the choir of St. John's College, Cambridge. The Darke version, with its beautiful and delicate organ accompaniment, has also gained popularity among choirs in recent years, after the King's College Choir included it on its radio broadcasts of the Nine Lessons and Carols. (Incidentally, Darke served as conductor of the choir during World War II.) A new musical setting by Jane Duzan Eubanks was premiered Christmas Eve 2009 at St John's Church, Randolph VT."