I have owned and tried lots of different brands, but by far the best is lululemon. There is simply no comparison in my mind. I wear my stretchy crop pants nearly everyday and I've owned my current pair for two years. The material is perfect--it allows your body to be at the perfect temperature (I've worn them in the summer and the winter). Also, the material is stretchy, but tight enough to serve as a smoother, but it doesn't bind or restrict motion at all. The only problem I've noticed is that the waistband is a bit loose, meaning I have to tug them up if I'm moving a lot. (This could just be because I need a smaller size.)
I wear them all the time as pants. They hide any and all panty lines, and you easily avoid any dreaded camel-toe. They also wick away moisture and don't retain odors. I can get away with not washing my pair for two weeks. Of course, it's not like I'm working out in them, so there's no reason they should get very smelly. After two years of constant wear, the pants are still in great condition. There has been no pilling at all, and I don't take very good care of them--just throw them in the washer/dryer with everything else.
Some people might complain that lululemon's clothes are too expensive, but they are practically indestructible. I think that they are actually very good value. I could spend $80 on a pair of pants that I will wear all the time for several years, or I could spend $30 on a pair of pants that will get gray and icky in a few months. Anyway, I'm always looking to add to my collection (they have really cute tops that I like to wear to spin and really good jackets as well).
I think these pants are the next thing I want to acquire. I like how they are skinny on the ankle, meaning I won't have to get them hemmed. Also, although the color is called Black Swan, it is actually a dark purple. I'm in a purple phase right now, and I would love some dark purple pants. Finally, these are sparkly. Admittedly, the sparkle is very subtle, but that's probably a good thing considering I'm not seven years old anymore.
If they have a good sale after the holidays, I might have to get these in red and gray as well.