What I find anymore these days is that online play really sells a game for me. I wind up spending a ton more time playing a game online if it's good than I do it's campaign. So I base it on value...am I getting what I paid for.
If I buy a game and it's only good for campaign...I only get so many hours out of it and then get that "I wonder if I should sell it now" feeling. If I play through a campaign and then spend a great deal of time online with it (like Halo 3 or MW2)...then its a gold winning game for me and I wont ever let it go.
So! To get to the point..I would choose MW2 as most of the reviews I have been hearing from people pretty much match yours.