Don't. Spend your money on a good competitive multiplayer game, like Chivalry.
Different genres entirely, at least say something like MW3 or BLOPS2 or CSGO. Tons of other competitive FPS PC shooters out there.
Lol calm down. In that case, I would recommend RO 2, BF:1942 (free on Origin!) or even Bad Company 1 or 2. If you don't mind a little Sim with your shooters, I also recommend ARMA 2. It has one of the most dedicated and creative mod communities out there.
Ewww.... Bad Company 1 & 2 were the worst games in the Battlefield series.