I've been listening lately to Legends of St. Nicholas: Medieval Chant and Polyphony by Anonymous 4. I've loved the Anonymous 4 sound since I first discovered them years ago.
from the little booklet that came with the CD:
Perhaps it was the beauty and widespread use of this Liturgy, along with hundreds of hymns to St. Nicholas and several music-dramas, that helped keep the amount of medieval polyphony in his honor relatively small. In fact, almost all of it that survives from between 1200 and 1350 is included in this recording.
You can listen to samples of the tracks at Amazon.