May I suggest both. Here are my two:
I ordered my 330i immediately after taking delivery of my Elise. Why? Because the Lotus is at the far end of the bell curve when it comes to daily driveability. The Exige S is pretty much the same car, but with a hard top and nastier suspension. The Lotus A/C sucks, the car is noisy and rough. However, as far as carving, not even the new M will be able to touch it (I know, this is speculation, but I'm no stranger to ///Ms); there is no other car that is as flickable as the Elise/Exige. And with my supercharger bringing the Elise up to 280 hp, an M3 will have a very hard time keeping up with it even in a straight line. Seriously, however, if you are going to buy one car, the new M3 is the obvious choice. Ungodly fast yet still refined and comfortable.