Get one that looks good in front of your house. Nothing looks worse than a stately home with a red minivan and a white SUV parked in front!
Should be a law that in certain neighborhoods, ugly functional common cars, if they are to be parked outside for 20 minutes of more should be the color of grass or leaves.
A red Porsche or yellow over here would look offensive for other reasons.
Silver/grey are good colors because the aesthetics of the car show up.
Blue, maroon, are merely owner's "favorite" colors and don't do the 997 justice, imho.