Having just sold my VW passat cc R V6 3.6 for the 428i GC, and used to swap once in a while to the S5 with my best friend, i would say the DSG is great, but not worth the headache that comes with it. Seriously my friend's S5 is always in the gearbox workshop, seen many audis there as well. And other issues that crops up not covered by warranty. My VW was into the 4th year of warranty and had no big issue but quite often visit the SC. So from ownership point of view, the VW And siblings not so great.
In terms of drivability esp quattro (4motion for VW), its great.... stable and all. But less interesting than the RWD beemer. Body roll more apparent than the 4 series, though the quattro helps a lot. Refinement and driving position, beemer wins it.
Engine sound, V6 hands down. The sound makes you just want to floor the pedal and the 330++ horses is awesome.