Whereas no-one could suggest that any version should take absolute precedence, it is reasonable in my opinion to suggest that the earliest extant print versions should carry greater weight than garbled oral versions.

If we take Bramble Briar as an example it is highly likely that the longer earlier American versions are much closer to the original than any of the English versions or indeed anything recorded after say 1900. Obviously we cannot deal with absolutes here in almost any ballad where the original isn't certain, but at least we can deal with strong likelihoods.