Modern Warfare 2 has too many problems and many people are probably buying Bad Company Two to get away from it.
I played the demo for BFBC2 and did not like it all, I love Call of Duty though, It has strategic game play and also "kamikaze" game play, If you will, I can't say for BFBC2 but the demo seemed all "kamikaze".
BC2 is much better than MW2. I played BC2 then MW2 and MW2 was just horrible after having played BC2
Its up to you. Battle Feild is involves more teamwork and MW2 is more of a soloish game. They are both fun though.
Since I'm a PC gamer, and MW2 sucked, I gotta say BC2
I love both of them too much to vote.
Battlefield: Bad Company Two > Call of Duty Modern Warfare 2.
I will have to chose MW2 with this one.
Battlefield Bad Company, FTW! The graphics are a lot more realistic and the campaigns seem to make more sense.