If you search the cadillac, Wolford stocking and pantyhose are really gorgeous. It's really the cream of the cream. They are really resistant,
the best quality you can get.
http://www.wolford.com
But, a pair of Wolford is really expensive. If you plan to purchase a pair, try to don't run them at the first time you put on.
My favorite brand is DIM. (No website yet.)
They are beautiful, resistant (depend on the series you purchase).
My favorite pantyhose is that brand is DIM DIAM'S voile galbé (20 deniers). I wear also DIM Sublim voile brillant (glossy sheer - 15 deniers) and DIM Sublim vole resistant (tactel - 15 deniers).
They are around 10$ each pair.
Secret pantyhose are cheaper in the price, but offer a good quality
http://www.secretpantyhose.com
Hope this info will help you to purchase a pair of nylon :)