A few years ago I purchased the CD set called, I think, "A State of Wonder", which had both the 55 and the 81 recordings, and also an interesting interview with Gould. If you were to categorize the interpretations, and they are quite different, the 55 would be romantic and the 81 would be classic - I tended to prefer the 81, possibly being influenced by Gould's comments (he trashes his own performance in the 55), but it does seem to me to have a greater sense of internal logic, and includes more of the repeats.
Having said all of that, if we are going to have a Goldberg Variations I would plump for a harpsichord rendition - Ralph Kirkpatrick, anyone?