I love my PS3 and I love a lot of the stuff on it.
But as a real favorite there can only be Demon's Souls. There has yet to be a more seminal game on any console (yes, Dark Souls was NOT as good as Demon's Souls in some aspects in my opinion), with a more immersive world and with greater gameplay. Demon's Souls is the epitome of what you can do with a minimum of characters and story details, and a maximum of care for your world and your internal consistency.
Again, I've loved most of what the console has offered in these past years...but Demon's Souls is the PS3 equivalent of Metro 2033 for me - which I consider the best shooter this generation -.























