The boxing metaphor is one way to compare, but another is to measure them against a standard of "great album."
Both have great sound, and are masterfully produced. The instruments--Bob's voice included--are tuned to perfectly complement the words. On the negative side to both: both suffer from comparisons to "previously unreleased versions." Desire suffers when Live75 is nearby, because its low-key, rambled, sultry Isis seems muted or even flat next to the electrical storm of Live75. Likewise, Idiot Wind from the released BOTT sounds hysterical and pointlessly obscure next to the somber, Poe-esque despair haunting the unreleased version.
Both feature tremendous lyrics, using a style which was completely new for Dylan, not simply a retread of his former ouevre. Desire loses a point here for the unknown quantity that is Jacques Levy. We'll never know whose brushstrokes were whose.
Bob's singing is outstanding on both records. The voice of Planet Waves and Before the Flood--that "I'm a Rock Icon" voice--is long gone, replaced brilliantly with a mature, muscular, courageous voice. A voice with less edge and more soul, more experience, more certainty--and less. Desire has both Bob's greatest performance (Coffee) and his worst (Joey), where BOTT is solid throughout, from the opening rasp of TUIB to the laconic stoicism of Buckets.
Both were successful. TUIB has proved to have greater legs than Hurricane, the movie notwithstanding. Neither record, however, would be considered Bob's biggest commercial product. Neither record resulted in a big cover, either, though covers have been done of several of these songs. (It is worth noting that Desire's "sound" is the foundation of John Mellancamp's entire success. The Jury is still out on whether this is good or bad.) Hurricane suffers under the weight of history. It is a song that no longer needs to be sung, on one level.
Both are unified. BOTT's common thread is lost love and the universe of pain, regret, longing and anger that accompany that great undoing. Desire is a travelogue, taking us from a New Jersey night to Black Diamond Bay to Red Hook to Lily Pond Lane. There are journeys within journeys, here.
Frankly, no argument for my personal choice, Blood on the Tracks, would be enough to sway anyone who prefers Desire. Like trying to decide between BIABH and Highway 61 Revisited (or between Down in the Groove and Knocked Out Loaded) there just isn't enough contrast to make a strong argument one way or the other.
PS I feel I must address Mozambique. Though the song is fluffy and light, that was clearly Bob's intent. In the spectrum of Desire's travels, it is a breath of ocean air. The historical fact of Mozambique's tragic social situation in 1975 is unfortunate, indeed, but does it really detract from this breezy beach number? Only to the unrepentantly serious.