Really? You want to get into a straight-line power dick-swinging contest? Planning to do 200km/h+ on Highway 1 with buddy in the Gallardo and Alpina B7 at night? I'll bite though.
G37:
+Luxury car with smooth power delivery
+Decent styling
-Not really practical if you want to haul shit around
MS3:
+Practical with the hatch
+Good power for the class it's in
-Tricky to increase power without supporting modifications (MS3 owners please confirm, I've read that the DISI engines are very sensitive to upgrades without Cobb AP, etc.)