I haven't played mw 3 yet but if you ask bad company 2 to compare with modern warfare 2 definitely bad company 2. Why i love the destruction and reality(Somewhat). Modernwarfare is not awful but when compare it goes for battlefield.
battlefield all the way, i have all the cod's and i love the series, but the feel of battlefield is unique, and plus you get to run over people with vehicles
COD Modern Warfare 3