The 335i is actually faster according to Motor Trend: 0-60 5.1 seconds, 13.7 quarter mile @104mph vs 0-60 5.4 and 14.0 quarter mile at 101.9mph.
I stand corrected. Probably because the BMW's torque is available ~3000RPMs lower than the G37.
Anyways, I actually just got a car in this range...I was only looking at sports cars/sedans. I test drove the 335, S4, G37, TL-SH AWD and IS350. I thought the BMW was the all-around best drive and the TL the best value (although it's ugly as sin). 335 climbs very quickly in price if you want to option it out to what a lot of the other cars have standard, but if you don't mind that, go with a 335. If you just want pure power, hard to beat the S4 (which is pretty damn nice anyways).