There are 19 million Kinects in the wild and very few good games to play on them. I think most people will say that Dance Central is the best (partially because it seems to work more than 75% of the time). What's second best?
It could be this holiday season's Fable: The Journey.
I grabbed some time to play the game on the final day of E3 last week. Then I filmed one of the game's developers play a boss battle. The video will explain most of what's good about the game: the simple but effective gesture-based magic-casting, the minimal need to control body movement (none of that silly lean-forward-to-move-forward from Kinect Star Wars).
Keep an open mind and give it a look.
One caveat: Early on, while I was shooting this, I stepped in a hole on the Fable: The Journey E3 stage. That's why, briefly, you can't see the game well. I didn't have time to re-shoot, so please just bear with it. And, no, I wasn't injured. Thanks for asking.