I invested in my first pair of Wolford a month ago and I am totally converted. I'm an experienced hose/tights wearer and usually can make them last quite a long time. But the Wolfords have a stretchiness and recovery and smoothness like my good dance tights, but are not nearly as thick. I've worn this single pair 3-5 times a week for going on 4 weeks now and there are no snags and no signs of weakening or bagging out. I swirl them in a no-rinse hosiery wash after every wear (it takes 15 seconds), since the wash is supposed to strengthen nylon. But Wolfords are supposed to be machine washable, and I have put them through the machine once. (The only "issue" is some marks where my red toenail polish and some dye from boots has rubbed off, and that would have happened with any tights.)
So I am totally a convert to Wolford! I don't think I'll buy anything else from now on. I got the "Individual 10" because I need a reinforced toe, but they have another kind that provides all-over support like Sheer Energy. Bare Necessities is running a 30% off sale right now that is valid on Wolford, BTW.