https://www.consumerreports.org
Some U.S. public libraries offer access to Consumer Reports for free with a library card.
sadly, consumer reports now gets money from purchases through amazon affiliate links
I would still place more trust in Consumer Reports than in for-profit review sites, but that trust has declined.
[0]: https://www.sleeplikethedead.com
[1]: https://www.sleeplikethedead.com/mattress-reviews-casper.htm...
That’s how i found a mattress that is still like new after 6 years of usage (and I’m extremely satisfied). And no, none of the “big” brand.
Here a rule of thumbs, avoiding a brand that start by “s” is already a good start. Then there is a few more to filter out.