I have about 10-12 pairs of Zella leggings in different patterns and styles that I've collected over the years to wear for hot yoga. They're the only brand of leggings that I'll wear to exercise.
Like featherwitch said, they wash very well, never fade, and no odors.
This year's black fabric is REALLY good. For the past couple of years, the black color has been a little "stiff", for lack of a better word - not as stretchy and soft. The high waist is great so you don't get the roll down as the day goes by. I also have the regular waist ones and those tend to roll down as I yoga. I have a bit of a tummy and don't feel any compression around my middle.
This year I bought both the black full length high waist and the 7/8th with pockets. The pockets gape out and don't lie flat against the leg and it bothers me, so those are going back.