Probably the McCormack would be easier to re-sell. However, if you are speaking value in terms of sound bought for the dollar invested, I might lean toward the Odyssey. Both company owners are terrific guys.
Your preamp will require fairly high gain to drive the McCormack if my experience with the DNA-2 was any guide. The Odyssey didn't have a problem with the gain of my preamp, which is 16dB.
I suppose the McCormack is the safer bet. The Odyssey might get you more power, and it'd already be upgraded with high capacitance and excellent parts that you'd otherwise have to have upgraded in the McCormack.
I had a fairly tough time selling my Odyssey Monos, which I bought used at a good price.