Demon Souls would have to be my #1 for this current generation. If you read anything I wrote in the past about Demon Souls you will know I love this game. I could reiterate that stuff but I am going to give you something new.
What makes this game stand out from every other Western RPG and JRPG out there is the fact its made for hardcore RPG fans. I haven't played a game like that since Oblivion back in 2006.
Final Fantasy, Dragon Age, Mass Effect are decent games, but they all went to casual. Yes its good to sell to more people yada yada. But when you ignore the needs of the audience that made you as big as you are to begin with, you really aren't that game anymore.
Demon Souls proved you can have a very hard game, that is a love letter to core RPG fans and still make money. But what makes it stand even higher is the sequel that is coming out this year Dark Souls, according to the developers is going to be bigger and harder then the first game, going further away from mainstream garbage.