A buddy of mine is an automotive journalist. I was looking at the M5/M6 and he steered me toward the M3 for three reasons:
1. reliability is better in the M3
2. DCT is far superior to the SMG III
3. M3 is more fun to drive (subjective)
Basically he drove both hard on track and briskly on the streets and felt the M3 was far better. The guy has driven almost every car made in the last 10 years so I respect his opinion. He felt the M3 was one of the best cars available today in terms of a sporty daily driver.
'07 Porsche GT3
'06 Honda S2000 #555 TTC
'08 BMW M3(sold)