Both Metal Gear Solid 4, and Call of Duty: World at War. Let me explain: MGS4 is an incredible game, with great graphics, and an incredible storyline. The game brings back all the characters in the series, so the other games need to be played to make it even better. The customizable weapons have great upgrades. It is incredibly realistic, as well as challenging.
CoD:WaW is a great game. The game navigates away from the 1,000 D-Day invasion games, and takes place in other infamous battles: Stalingrad, Midway, Okinawa, and Berlin. This makes the game more fun because it isn't about the invasion of France, which is considered boring, because it has been made many times. What stands out, however, is the online. I love to customize the weapons, which are a lot of fun because they are old guns. Another fun thing is Nazi/Imperial Zombies, playing solo or online with up to 3 other people, getting fun weapons to stand against a zombie invasion.
I personally think that Metal Gear Solid 4 is a little better.
