Well i think this is a great question cause we talk about the comeback of the two bigger new IP of 2014. (after Destiny, though Destiny 2 won't come this year).
The first Watch_Dogs as we know has outsold Titanfall by an huge margin, cause while Titanfall was PC/XBO/360 Watch Dogs was on PlayStation too. In short, bigger userbase.
Now that Titanfall has the same userbase, both will be PC/PS4/XBO, what are you'r thoughts?
I will go with Watch Dogs 2, because Titanfall will have a lot of competition from Battlefield 1 and Call of Duty Infinite Warfare. I expect both to be close though.