I think Audi's are great cars but the performance figures for the new RS5 aren't that far off from the M3. You also have to remember that the M3 is going on 5 years of age ,so, I would hope Audi would bring some comp. to the table. I personally don't like the huge front grills that most of them have now but that's strictly my opinion. Audi's have a good quality build, nice interiors and are amazing in the snow!
Good luck with your decision