WD's attach rate on PS4 is probably gonna be higher than MK8 on Wii U, so the "only on one platform" argument is not good enough to put MK8 above WD in my opinion. It's a new IP too. The fastest-selling one in history!
I'm gonna go with Watch Dogs.
No troll is too much for me to handle. I rehabilitate trolls, I train people. I am the Troll Whisperer.