It really depends on WHEN you played certain games.
For instance, If you played EverQuest back in 1999, you would probably consider that game to be in your top 3 easily...It being the first fully realized 3D Massively Multiplayer Online Game with a dynamic world.
For Me, I would have to go with Little Big Planet 2....probably because im a creative person and that was Easily in my top 3 of all time.
...uhh...ill just put my favorite quote of all time here.
"Welcome to Pain, the second of three...You have dealt the first...now deal with me!!"