I did not post this under the Tasting Notes section as I did not really take any formal notes.
Both of these wines were drinking very well currently, and clearly no need to rush and drink soon.
I found the Haut Brion to be a little reserved and more of a classic Bordeaux if you will, ( thinking Upper East Side, NY) and the La Mission more vibrant and racy, yet still Bordeaux, without debate. ( Upper West Side, NY)
Based solely on these two bottles side by side, I would give a clear edge to the La Mission, but would never say no to the Haut Brion.
Both examples of excellent wine making and excellent Bordeaux, in my opinion.