I don't tend to go for designer labels in clothing, not that I really had the option when I was bigger. Some of the sportswear branded stuff seems really good though, my
Altura fingerless gloves are really comfy, my Skins winter gear is utterly amazing as are a few other bits, my Asics running gear is so much better quality than
Nike and other stuff.
Sometimes, but not always. Some labelled stuff is no better made than relatively cheap stuff... I had a couple of pairs of Primark 3/4 length trousers that saw me through two summers of cycling, including hundreds of miles of touring in France, and cost £3 each.
And with food, you're often buying the same things with different labels. I gather Nabisco make Weetabix, and then they make Wheat Bisks for supermarkets. Much of the 'Basic' or Everyday Value stuff in supermarkets is the same as the 'normal' own brand, just repackaged as a loss leader.
I went to Primark for the first time a couple of weeks ago, I bought a couple of plain T-shirts partly out of curiosity, figured for £2.50 each I'd just use them to clean my chain if they were rubbish, but they're better fitted and more comfy than a typical £15 T-shirt I'd buy. You could argue the fabric is less 'fine' close-up but it seems more hard wearing and stands up much better to cat claws
I find the value stuff a bit confusing as some of it is pretty gross, but some is the same as normal and to add to confusion, some branded things in Tesco's are actually Tesco's brands pretending to be an independent.