Hard to decide, maybe Phantasy Star Online, but that's more for the people than the game. I love all the Final Fantasy games I've played (7 to 12, excluding 11), Borderlands, Morrowind/Oblivion/Skyrim and the Fable series
A little birdy told me it was your birthday! Well yesterday, I am late but wanted to say Happy Birthday anyways! Hope u had a wonderful day full of cookies! ^^