The RS4 when its released wont be anywhere near the M3's price range, its going to be much more expensive. If you want to compare an Audi it would be the S4 which gives you the benefit of AWD so you can drive it in the snow, but it lacks alot of the feel and power of the M3.
M3 hands down. Coilovers and 4.10 gears with top end software and it will be an even bigger monster if you dont mind the harsher ride and shifting a bit more often.
