Being an adrenaline junkie and living 15 minutes from a six flags, being in the front gives you an "open" feeling" where you can see everything.
The back of the car is more of a thrill, as when you're going over a hill, you get whipped over, because the front of the kart is falling, while you're still somewhat going up, therefore, going "faster" in that particular area. You feel like you're being pushed if you're sitting in the front, in this situation.
For the ride enjoyment, go in the front, (though, the line might be a LOT longer) for thrill and being whipped around, go in the back.
Personally I enjoy the back more.