Should I buy Arma 2 or Stalker: CoP?

I know the games are kind of different, so it's weird I'm asking, I beat Shadow of Chernobyl, but do you think it's worth continuing on in that series or should I try something new (Arma 2)? It intrigues me because of its focus on realism.

Stalker is an awesome series. Arma 2 is a hardcore mil sim. I would say try the demo for Arma2, it is not for everyone, but it is more about playing multiplayer than single player. Stalker is the opposite.

STALKER if you want a fun game...

ARMA 2 if you...want a simulator?