To follow on with Obliterator1700's theme.
Mine would be Metal Gear Solid 4: Guns of the Patriots
End of 2014 Hardware Predictions (03/03/14)
PlayStation 4: 12-15million
Xbox One: 7-10 million
Wii U: 8-9 million (Changed 01/04/2014 from 7-9 --> 8-9 million)