Depends on your playing style my friend.
Littlebigplanet - Had a big following when it first came out. It has puzzles to solve and items to collect. Levels made by other people you can download and play which might extend the experience. One and Two player levels to solve.
Wipeout HD Fury - Shooter. Rotate around a world and destory stuff. Repetative same old stuff. Unless someone else has another opinion.
Dead Nation - FPS which I have not played before. What can you say about FPS but go out and shoot stuff.
Hope that helps.