this one is easy:
FFXIII will sell around 450-500k (if not more) ps3 in the first month in japan only because, as some guy allready wrote, the whole FF-fanbase still didn't switched to next-gen. on the other hand, the COD-fanbase allready is on PS3/360 so the MW2 bundle wouldn't sell as good as the FF bundle.
so my vote goes for FFXIII