As the owner of a 330xi, I say get the 325i. RWD is more fun and gets better mileage. With a set of good winter tires, you will get pretty close to AWD traction.
When you decide on a vehicle, remind the dealership to NOT touch the vehicle and get it reconditioned right away by Apollo Detailing. Dealerships use glazes and generally make a muck of a good trade. Used car dealers are the worst. I remember seeing a 1998 Ferrari Spyder a while back at a dealer in Richmond Hill. When I saw it a day or two after its arrival, it was in decent condition and only lightly swirled. One week later after a dealer wash, the Ferrari looked like it had been washed with steel wool and dawn.
Needless to say, I have more advanced techniques.