M3 is a great car with some nice touches but ugly looks and fake engine noise. The M cars will always be great track cars and each generation gets faster and faster. The QV is showing its age from a absolute speed standpoint (not to mention technology). However, if I wanted the ultimate track weapon, I would buy a Corvette or GT3RS.
I love my QV. It is a great driver's car and will be a great driver's car in 20 years when we are all riding nuclear powered hoverboards. So will the M3, for that matter. But, in 1-3 years, there will be a faster super saloon that will beat the M3 and the cycle continues.