I like Audi's styling but I have found BMW to be much more reliable and a better balanced chassis. I used to live in MN so Audi Quattro was great for winter driving. I used to have an RS6, S4, S8 and a Q7. All of those cars had odd repair needs. S4 needed a new transmission after 12k miles, Q7 needed an engine repair that took 2 weeks (at 20k miles) and the RS6 had recurring suspension issues. The S8 had a weird electronic glitch that required a reset of the computer to fix (found this out after two shops made multiple attempts to fix over a few weeks). I think Audi is improving but I have had 0 issues with my M3 after 36k miles. Same was true for my '05 e36 M3 and '01 328i back in the day....
'08 E90 M3 - Alpine White - Sold
'13 E92 M3 - Silverstone II - Sold
'04 E46 M3 - Jet Black - BBS E88, KW Clubsports, Brembo BBK, SuperSprint Exhaust