I am not a fan of either, as I play video games for the story, and both of those lack a decent one. (In my opinion.) For pure multiplayer enjoyment, though, I prefer BF because it is slower paced than CoD, and I am a pretty slow paced person. I cannot keep up with the action on CoD, personally.
Halo is iffy for me. On one hand, I adore all things space and sci-fi, so its inherently fun for me. On the other hand, it is pretty iteretive, though Halo 4 was a step in the right direction.
Anybody have Titanfall?
I assume since you love story you played the mass effect series ?