Originally Posted by michaeldorian
I previously had an RS4 and can definitely agree with this statement. As a DD, the RS4 was a better car. The low-down torque curve made the car much easier to drive. The AWD was planted in the rain, and the overall build quality was better. (Interior, Exterior). The gearbox was one of the best I've driven. Very light and smooth. The RS4 also has more of a presence on the road as it was wide and pretty rare. Stock for stock the RS4 is more bang for your buck. Especially used in the mid to high 40's.
With the M3, you really have to be above 5K to really experience the car. The car feels much smaller, nimbler, and sportier in that rev range. It begs to be driven. The car revs much faster. The throttle response is also sharper. The seats in the M3 are also sportier. For me, I wanted something that was a more challenging and rewarding to drive and the M3 definitely delivers on that front. It's an overall sportier car.
If deciding on fun factor M3 > RS4
If deciding on practicality RS4 > M3
I don't think there is a right or wrong choice to be had with either. From a personal note I feel (after sampling the M3 in icy road conditions with summer tyres) that the RS4 is the better daily drive and wins this hands down. I can't answer how an M3 is with either proper winter tyres or chains in more extreme conditions but on more normal slippier surfaces were changing to winter rubber would be over kill the Quattro system with the RS4 is superior.
Build quality is harder to gauge because unless things go wrong you can't really aswer that question, I think after owning both Audi and BMW that the Audi's switch gear gives the feel of being better and it's interior design looks the more exciting though some may find it fussy.
There is little doubt that when really going for it the M3 does show it's metal and is the more exciting to drive but at less than 80% or even 90% the Audi might edge it on overall appeal. The RS4 is rarer but it's almost the older model and for that reason alone I went for the M3, but then again I was buying new.