Black. But more important than the colour is that they are warm enough, space under for long johns, and are waterproof/wind proof. The quality and price of ski pants varies so much that it would also have been helpful to know your budget. How much you spend may also depend on how often you will wear them. There are stretchy, waterproof outdoor trousers that you could use for other purposes with ankle "flaps" for over ski/hillwalking boots. White ski pants are popular but only look good newly washed and I guess you want to wear them for six days on a holiday.