Traditionally, all BMWs have sold better in black.
But in 2012, grey was the new black, and I'm sure many haven't caught up that this is already old, and buy grey to match everybody else.
(And some just because they like grey, of course)
So my guess is (for the US market, where we don't get a lot of colors):
Grey > Black > White > Silver > The two dark blues > Beige > Orange > Le Mans Blue