It depends on the pants IMO. You should wear them how they are meant to be worn. If you have low rise pants, don't try wearing them high, you'll look ridiculous with the pants riding up your ass.
Ultimately, I like them above my hip bone (illiac crest area), the way it was described above.
However, I think there is an important way to wear the pants to be most comfortable:
The thing about wearing your pants at your true waist/hips/illiac crest (or higher) is that your stomach gets in the way. Doesn't anyone else find this a problem? I'm not talking if you have a fat stomach, I have 30" waist and low bodyfat, but pants that fit at my "true waist" get in the way of my breathing. To get around this problem, I wear the front of my pants a tad lower. It's similar to the way in which I wear my hip belt when backpacking. The hip belt goes over your true hip bones/illiac crest, but so you can breath, the front of the belt goes lower.
Personally, that problem is also why I do like wearing low rise jeans and stuff because I actually feel it's a bit more natural feeling sometimes.
But regardless, no idea how people wear anything directly over their stomach. Unless you wear them loose with suspenders. That's about the only way.