Coffee, you really get what you pay for (at least up to a certain price point)
Shoes, good shoes are much more comfortable and last ages. I have a pair of strappy leather sandals that were £50 10 years ago and still going strong.
Furniture solid wood is just better than flat pack chip board.
Matresses (and matresses over bed frames as you don't exactly sleep on the bed frame, it's just something to put the mattress on)
Lego, the real stuff is better quality with insanely small tolerances in manufacturing
Skin care. I have ridiculously sensitive combination skin. Enough said
Coats. I grew up poor so mostly had Ethel Austin or supermarket coats, then was a skint student so still couldn't afford a high quality coat. The first year I could afford a decent warm welcome properly waterproof coat was a revelation. It hit me some point in mid January that not once that winter had I shivered with cold whilst wearing my coat outside, for the first time ever. It lasted years too and I only don't wear it now because I'm too fat for it now. My ds now also gets an expensive coat (despite dp's protests 'because he'll have grown out of it in six months', and he has never once cried because he was so cold, something that happened to me every winter as a child)
Tinned tomatoes. I like the polish ones
Toys. My ds gets less but more expensive toys, that don't break as soon as you look at them. So he doesn't get upset that his toy car he's had for a week suddenly has no wheels, and when he's grown out of them they're still in good enough condition to pass on.
Chocolate. Cheap chocolate is gross and I'd rather have no chocolate at all than eat greasy brown sugar.
Perfume, like a pp said, copies just don't have the staying power. Doesn't have to be super expensive, something like paco rabbane lady million or Paul Smith rose will do, but they definitely last longer and smell nicer after drying down than say new look or lidl ones.
Flooring. Decent flooring lasts ages so works out cheaper in the long run. It's vimes boots theory all over with 90% of stuff. Buy cheap buy twice.
That said stuff like toilet roll, socks, kids clothes are fine cheap. Ds is
in clarks m&s shoes and coats but primark clothes. And the cheaper the sausages the better they taste 