Sometimes spending a bit more returns big dividends. I like my vegetable peeler which cost a bit more than the el-cheapo, but is a joy to use. I also like to use 25# paper in my printer instead of the 20#. It has a much nicer feel.
What else?
A mattress. Get the best and most comfortable one you can afford. It’s like commercial says: you spend a third of your life on it (ideally).
Shoes
Furniture
Bras
Good knives. You don’t even have to spend a lot - I like the Victorinox ones Cook’s Illustrated recommends - but the difference between a decent knife and the crappy ones at other people’s houses is extreme.
Cheese
Funnily enough, the advice I get is “they’re all made out of the same cheapo materials excepting memory foam mattresses, so just get a normal one and add foam padding to the top as needed for your comfort” Personally I followed the advice, paid $450 for my queen mattress and am over the moon with it so I’m inclined to agree.
Now, spending more on paper and cheese I can definitely get behind. Getting the real parmigianio reggiano is definitely worth it. I’d add tea to the list - good tea is miles better tasting.
Fuel with no ethanol.
I agree. I just replaced one that broke - I’d had it since I moved into my first apartment in around 1996. I bought the same kind, even at $18.99. Plus, it works well.
Chocolate
Winter outerwear
Reading/craft lamp
Scissors
Fountain pen, ink, stationery, journals
Sometimes I think I’d willingly go bankrupt over the perfect leather purse.
Body lotion.
You can use the cheap stuff and still feel dry and flaky. Or you can spend a few dollars more and feel like you’ve rubbed velvet into your skin. The difference is amazing.
Kleenex with aloe.
If you’ve got a bad cold and you’re gonna blow your nose a hunnert times a day for the next week, spring the extra dollar or two and get the soft kleenex. Your nose will thank you.
Quality toilet paper. You don’t cut corners here.
Almost 20 years ago I paid more than I had to for a Maytag washer and drier pair. They are still working, look like new, and I thing I’ve spent a grand total of about $200 on repairs. The two times I did have repairman come out, both times (different guys) they said, don’t ever sell those, they are built like a tank and will last you the rest of your life.
So true!! My former workplace had single ply industrial grade TP in the restrooms. Really made me appreciate the good stuff at home.
Tool blades. Most hand tools, for that matter.
I second kitchen knives and Victorinox makes some damn fine ones for a very reasonable price. My 8" butcher knife from them is as good or better than knives that cost 5 times more but infinitely superior to a cheap stamped knife. Sometimes, you don’t even need to pay more to get great quality. You just have to know what to buy.
The others are power tools, especially chain saws and lawn mowers. Cheap versions of those will cause you nothing but heartache and huge amounts of time and money if you do any significant work with them whatsoever. Get a reputable mower like a John Deere and a good chainsaw like a Stihl. They don’t cost that much more than the cheaper brands and it is very cost effective even in the medium-term.
Oh, TP, definitely. The el cheapo TP that sells for a buck per four-pack is loosely rolled and lasts, maybe, four days. Scott or other better brands that sell for $4.00 per four-pack lasts a month.
Shoes. The woman who works for me, her husband and another couple of poor people I know, buy WalMart (or equivalent) plastic shoes for less than $20 - once or twice or even three times a year. I have shoes I spent between $100-150 that have lasted me ten-plus years and still going like new. You do the math. And they are not even water-proof, or that warm.
I also know someone who pays rent-to-own prices for appliances, furniture and a lap-top. That is just fucking insane. She is paying, literally, 10x the value of what she could buy brand new on a sensible plan if she could rein in her want list for a month or two, or 20x what she would spend on a carefully-considered craigslist item.
Electronics. I always buy more than I need, and discover I need more after all.
Anything that is intended to keep you warm and/or dry.
Hookers and blow.
And on a serious note, throw another vote up for toilet paper.
That’s the first thing I thought of, too. We have bought two good quality beds now, and they’ve both been fabulous.
That’s a running joke in our family; we were doing pretty well financially in the last couple of years, so I came home and told my husband, “I’m feeling pretty flush these days - I buy the fancy cheese now.” 
Ow. Ow ow ow.
I’ve recently switched to (what I hope is) cruelty-free meat, and by God, it’s not crazy expensive, and it really does taste much better.
I’ll second or whatever shoes, too. What really bugs me is when I spend a good amount of money on a good pair of shoes, and they break down in a month. This is not as advertised!
I’m starting to think cameras might be one of these things, too - I’ve had two cheaper cameras (a Nikon and a Samsung), and both broke down far too soon.