List of all licencees: https://www.blu-raydisc.info/licensee-list/discmanuid-licenseelist.php (basically anything that is not single layer is always HTL type)
French study looking into archive quality of different brands: https://club.myce.com/t/french-study-on-bd-r-for-archival/302333
Panasonic followed by Sony are the best for longevity according to the study. However, neither are widely available outside Japan.
Acu-disc are a supplier of HTL discs widely avaiiable in the UK and have good reviews, although no independent evidence to compare them to the big name brands https://www.rpadistribution.co.uk/5060158312948/Acu-Disc-%C2%AE-Blu-Ray-10x-White-Thermal.html
The diagram on that page looks exactly like a Panasonic one – maybe they are the same fabricator? Possible, but after contacting BlyRay licence office, they said “As they do not use the BD Logo ad have no license from us, we cannot guarantee that their products are legitimate or compliant.”