Battlefield Bad Company 2 or Modern Warfare 2

I’ll be on BFBC2 when it comes out, because as far as I can see from the demo, this game is way better than MW2 for online gameplay.
I’ll still be on MW2 though as all of my friends have it and the multiplayer unlockables and challenges are neverending so I can keep playing it for a while.
I’m worried that battlefield will be limited in its online playability.

So what do you guys think?