My Top5:
1st: Full Spectrum Warrior (XBOX, PS2, PC) [Gameplay simply ruled.]
2nd: SOCOM II (PS2) [All-around goodness.]
3rd: Battlefield 2 (PC, XBOX, PS2) [Amazing multiplayer mode.]
4th: Delta Force: Black Hawk Down (XBOX, PS2, PC) [Gives a good feeling of what war in Africa and Middle-East...