This: (Just got it for PC)
So far, it's great. I came to this from regular ol'e Battlefield 2, and it's a massive difference. Completely destructible environments (which makes cover freakishly temporary... especially when someone can bring an entire building down on top of you), realistic projectile physics (bullet drop, penetration, etc.), Great improvement from BF2 in terms of feel, response, and graphics... plus, singleplayer has a campaign mode with a story-line and great dialogue.
So far I'm just giving the campaign a run-through, then it's multi-player online.
Anyone else play this?