I agree completely with Mike. Having gone both ways, I can say they are both great. You cannot go wrong here. The way out of Triacastela for San Xil starts out on a highway, but soon it takes you up onto ancient cart paths, it is magical. The way to Samos is also beautiful, I remember a field of lupines that knocked my socks off.
I will say that though I may be in the minority, I think the paintings on the walls of the Samos monastery are uninteresting, cliched, and not of a very high artistic quality. But the view of the monastery before you descend to Samos is fabulous and inspiring. The albergue in the monastery is damp and dank, but there are several private places to stay as well.