I would chose Black because White shows dirt or about anything you had on your hands when you touched it, and I haven't seen many Gray Laptops.
I just got a blue sapphire one, so I would suggest a dark color. If you are going to be taking it out at business functions, it looks more professional, but it depends on what you are using it for. I would expect a business person like Donald Trump to have a dark colored laptop, and someone like Paris Hilton to have a white, or pink one. JMO