The 3.0T A6 seems dam near perfect. I'm impressed every time I drive it.
Drove a 2.0 A4. Nice car. More tossable. But I disliked the near constant, noticeable downshifts.
Think about the kind of ride you want. More sports car: get a Prestige with larger wheels and summer tires. Not the best for areas with rough roads.
The Premium Plus with 18" wheels & Conti's gives you a tight, but more elegant ride. Almost feels like completely different cars. No right or wrong answers, just get what you want.
2012 3.0T A6 Quartz Gray Premium Plus
1973 Audi Fox (80)
2014 Morgan Three-Wheeler