I think it might be Portal 2. The roller-coaster of emotions I was in when I finished it has been unrivaled.
Joy, of winning.
Fear, of being shot by turrets.
Pity, for GLADos.
Awe, for Valve and their creation.
Sorrow, because it was over.
Utter amazement from the turret aria and the fantastic last portal.
Mindblowing stuff.
Other than that;
Mass Effect 1 and 2
Witcher 1 (because it is one of FEW games nowadays that took the time to finish properly and WITHOUT a cliffhanger. THANK YOU CD PROJECT!)
Legacy of Kain: Defiance. The reunion of Raziel and Kain almost brought tears to my eyes.
Final Fantasy 8 and 9. Epic stuff.
The Whispered World. Pretty good actually. And a BEAUTIFUL game.
There are more, but there always will be.