I've always been a Sony gamer, through and through. I did, however, get a Wii a couple of years back which introduced me to the idea of motion-controlled gaming (I even used my Wii Fit for about a month).
Then, in April of this year, I got a PS3 (just the 160gb model, no Move). However, I never thought I'd get an Xbox. I fought against it tooth and nail. I made fun of people who had Xboxes and swore that the PlayStation (whichever version at the time) was the best console. While I'm still primarily a Sony gamer, I've started to change my tune. It's the Beatles all over again.
Having already tried out the Kinect with various games, when the opportunity to get the system presented itself, I took it. Now my brother and I can run track-and-field against each other, despite the fact that I could never actually finish a hundred-meter dash even if Felicia Day were waiting at the finish line. Now I can whitewater raft in my living room with my two-year-old niece until she tells the Xbox "We're done!" I don't even have to mention the lack of "necessary accessories" that burn a hole in your wallet quicker than you can say "He's on fire!"
Sure the Xbox is also great for hours of reliving the glory days with Perfect Dark or running bobble-headed players around in NBA Jam. I even appreciate the clever marketing around some of the new console launches (I've considered selling my current Xbox for the upcoming Star Wars edition just about every morning since I read about it). But, what really sells it is the Kinect. When it comes to motion-controlled gaming, the Kinect takes the cake, and helps me burn off the calories at the same time.