Counter Strike is the best multiplayer shooter ever created. The fact, that it's the only shooter to captivate milions of players for over a decade, the fact that it evolved into a sport and you can earn thousands of dollars playing it, clearly states who is the multiplayer king around here.
I don't like singleplayer shooters, but from what I've played, CoD 4 would be my choice, even though it wasn't a perfect experience.
Lately I've been playing a ton of MAG, since it's the only shooter that doesn't feel dumbed down with aim assist and arcade game style.
MY HYPE LIST: 1) Gran Turismo 5; 2) Civilization V; 3) Starcraft II; 4) The Last Guardian; 5) Metal Gear Solid: Rising