I reckon that U2 will sell more. I think L4D2 will do well especially as there aren't that many exclusives left this year...but reckon that U2 will seel better due to the perception of the game as well as the much better PS3 sales this year compared to last with the price drop.
The PS3 will be the machine to have this Xmas and U2 will be the game IMHO.
Prediction (June 12th 2017)
Permanent pricedrop for both PS4 Slim and PS4 Pro in October.
PS4 Slim $249 (October 2017)
PS4 Pro $349 (October 2017)