the only thing making me say modern warfare 3 is im invested in that story.....im one of the few people i know who actually will buy an fps for the single player (if it is good)
ive been following the modern warfare story since the beginning and want to see where it goes
ive never really played a battlefield game but from what ive been seeing of 3...it looks pretty awesome....ill probably end up playing both and i really dont see myself not enjoying them
but yeah....im gonna say modern warfare 3