Having owned both, I can say I like the M3 better. The M3 is much more rare, more comfortable, faster in almost every way, everything works better- especially A/C, power windows & headlights - probably because it's 9 years newer. Having said that, the 911sc might get to 60mph a tick quicker, and there is some intangible feeling that a 911 has. . . maybe its the sound (and torque)of that flat 6, maybe its the beautiful shape. I occasionally miss my 911, but I love my M3.