Which is better dead rising 2 case zero or dead rising 2

Dead Rising 2: Case Zero is nothing more than a prologue to the Dead Rising 2 game. It gives the backdrop as to how the main character, Chuck Greene, ended up in the situation he is in with his daughter Katey. In all respects, Dead Rising 2 would be the better game to purchase, since Case Zero is a downloadable game on the xbox live marketplace, and not a game that can be purchased in stores.