Mw2 Sold >1.80m units in its opening week 1.78m ~90%.
Black Ops 2 Sold less than it althought 60% of the sales were from the 360 version wich should put it above 1m mark in the United Kingdom alone.
Black Ops 2 Launch achieved over $500m WW in its first week and Mw3 $400m in the UK and US Alone, so that probably puts Mw3 above Blops 2.
Lower sales for Black Ops 2 might be explained by the launch of Halo 4 Last Week wich was huge on the 360 achieving over $300m in its first week on sale.
Although Lower sales on the UK doesnt mean the whole story since GameStop just said this was the biggest Call of Duty midnight opening with over 1m copies sold.