I was going to share the Food Lab specifically, especially this cookie recipe:
https://www.seriouseats.com/the-food-lab-best-chocolate-chip-cookie-recipe
I made it my goal to test each and every element, from ingredients to cooking process, leaving no chocolate chip unturned in my quest for the best. 32 pounds of flour, over 100 individual tests, and 1,536 cookies later, I had my answers.
Finally, a thread I feel like I can contribute to meaningfully. Your example is fantastic btw. I could not care less about marinara, but that was a great read.
Due to foot pain I went through around 20 pairs of running shoes and went to two run labs where they filmed my gait in slow motion to figure out why I couldn't run more than a couple miles. Knowing what sorts of shoes work best for me was a good outcome of paying the one time costs.
the entire Wirecutter website, until they sold out and became ads. Consumer reports may still be that way as well.
The German Stiftung Warentest does this, too. Their title roughly translates to "foundation for testing consumer products".
unsure if this applies but pannenkoek2012 is known for having done an immense amount of research into the Super Mario 64 A Button Challenge; this is similar, though not quite the same, as speedrun strategy research.
Ask Raemon. Seriously, do it. If there's a combination of words that's extremely valuable (e.g. best AI safety introduction, highest EV rationality technique to try, etc) and it's on Lesswrong, Raemon has a track record for doing a lot of work to find the best one.
James Hoffman's coffee videos have this kind of vibe. The "tasting every Nespresso pod" one is a clear example, but I also really appreciate e.g. the explanations of how to blind taste
Best flashlights (from /r/flashlight): https://zakreviews.com/arbitrary-list-2023.1.html
Aaron Collins for mask reviews
Enthusiasts of {wine/coffee/whiskey/potato/etc.} tasting?
It's a very interesting model of the world that tastes 18 different brands of store-bought sauce and doesn't compare it to just making your own. Add "seriouseats" to any recipe-related query and you'll get recipes that both work and taste like they're supposed to. They may eventually fire their writers and replace them with AI trained on blogspam recipes, so exploit this knowledge while you can. Surprisingly few people know about it, given how much utility basic culinary knowledge can add to your life.
My example: Marinara sauce: https://twitter.com/tresterese/status/1684024122278281217