16" wheels are lighter, tires are less expensive and the ride there's less noise, vibration & harshness (NVH). My car has 17" wheels (I ordered my car with 16" wheels but they showed up with 17") but in the winter, I run 15" wheels and snowtires. Huge difference in ride. However, handling capabilities is reduced slightly.
I think if you're not concerned so much with the look of your car and don't need the ultimate in cornering (which you don't in normal street use), 16" wheels are probably a better overall compromise for most people.
That isn't to say, you can't get lighter 17" wheels and a different tire that performs better. Just personal thoughts on the subject.