HardcoreSadism-I for one will happily white knight Sonic06, I think it's a highly underrated game myself. It was actually the very first 360 game I ever played, so for me it holds a special place.
I would say the PC game Limbo Of The Lost is a much better contender, seeing as almost every piece of art of the game was plagarized from other games(I.E. Unreal Tournament 2004, Thief: Deadly Shadows, Elder Scrolls Oblivion, Painkiller, etc, they also stole some movie clips from Spawn and one of Pirates of the Carribean films) and it was actually pulled from store shelves over the controversy.