Underrated Über SedanS

Not sure if anyone got to see this with the Kinja mess so re-post: So the Mercedes S63 AMG has 577 hp and hits 60 in 3.9 seconds, but the Audi S8 has 520 hp and hits 60 in 3.5 seconds. I realize the 0-60 numbers on the Mercedes are not official yet, but it seems that the S8 is a rather under-appreciated, super-quick, luxo-barge. And just for my personal tastes, I don’t care for some of the styling awkwardness of the new S-class. I dig the Audi, it has a nice stealth-factor. What is your pick for a full size executive sedan?