at first i didn't like the c63. but eventually the interior and the standard features list got to me. but i will say this m3 sedan<c63 but m3 coupe>c63. although you are getting a 6.2l with the 63 it is an automatic, nothing wrong with that but the m3 has manual and the new godlike 7 speed ksg
the driving feeling of the amg and ms are way different to. the m always feel driver oriented making the driver really have feel for the car. the benz on the other hand is just a bullet. push the pedal and your out. nothing really special to the drive to it.
this is from riding and driving m coupe, m3, m5, c55, clk55, sl55, e63, and a slk55.