Right now barcodes appear to take precedent over any relationships, which is wrong because we can't fix wrong cover art.

Apparently the next server release will prefer ASINs, then cover art links, then barcodes. This is still not ideal because an ASIN can still be valid for the release even if the cover art is wrong (or is very poor quality or whatever). Therefore cover art links should always be chosen first, followed by other relationships, then barcodes last.