I am by no means a driving expert, but I have been able to drive many nice cars including: 996 turbo, 996 C4S, e46 M3, 997 GT3, C5 Z06
By far the two awd 911s are less exciting, less fun to drive than the RWD cars. I do not say they are bad cars at all, but mainly I am looking for a fun car. I could explore the RS4 audi rahter than the M3 or as you point out a 4 year old 911 turbo. But IMO AWD (while a nice feature in some instances) is not the best driving for a sports car.
Also, the M3 either one, will have a greater rear seat.
Here is the M3 coupe rear seat vs the 911 turbo take that for what you want.