The two games are different. Modern warfare and MW2 are about close quarters fighting and twitch response. The battlefield series is more about large open maps and vehicular combat. Each are good in their own right. Modern warfare is a visceral and satisfying experience, but for me it got very old very quickly. Bit like Halo 3 after they released the Legendary map pack. I have spent more time playing BF1943 than either of those games, simply because it's bigger, and there is more to do