Try the G35 sedan. More power, good handling and nicely done inside. Of course it will be a little bit more than either car you are looking at, but it's worth the price. The maintenance cost is also much less than the BMW (you either will have no free maintenance left from the factory, or if you get an '03, you'll have about 2 years). Also, if you do opt for the 3 series, get the '03 with a late in service date and do not get a demo or a dealer loaner car.
Good luck and let us know what you purchase.