Is this going to be one of those bot threads that we turn into a serious thread?

In the case of strategy, my favorites are in the RTS genre with Command & Conquer (Red Alert 2 and Generals), Warcraft II and Age of Empires II.

As far as action games, Battlefield and Call of Duty have both made a couple really awesome games, especially in the last few years. As far as campaigns I really loved BF3 and Modern Warfre 2, but for multiplayer my favorites might be Black Ops and Bad Company 2.

Of course a special place in my heart is Killzone, particularly the second one. I don't think anyone's ever made such a surrealistic experience to put you in a warzone, from the movement, the gun-handling, the visuals, the sounds, the animations, etc. etc. etc.