As a current '06 S4 owner who is counting the days till the E90/92 M3 shows up, i'd still probably say RS4 based on AWD and all that it has to offer. However The M3 is an M3 and there is just a certain mystique about the car.
2009 E90 M3 | Silverstone II | Black Novillo | HRE P40's | Akrapovic Exhaust | Eibach Pro Kit | Jet Black Kidney Grilles | SSII Side Reflectors | SSII Side Gills | LUX H8 Angel Eyes | Macht Schnell Filter | Tecnocraft Envy Charge Pipe
"M3 drivers have no friends." - Jeremy Clarkson