I know this will depend on the denier and type, but in general. I am sick of my tights lasting me hardly anytime at all, it's very annoying and expensive.
Sheer, skin coloured tights that I wear in summer to make my legs a bit more acceptable I get from Evans. I find these to last me the longest of that type. I have had Boots and Primark ones but they rip on the first wear for me.
Black tights I tend to get from Tesco or Boots. I find them similar price and quality. However after maybe a weeks worth of wear they start to rip at the crotch.
I normally try to get a size too big in the hope they will last a bit longer.