LONGECITY

Two guide here, most websites that rate brands don't even include the best ones.  

https://www.fixyourg...ment-companies/

https://www.optimusm...plement-brands/

By no means complete, they don't mention Livon Labs for lipsomes or longevity companies like

-Renuebyscience.com

-quicksilverscientific.com

-revgenetics.com

-ProHealth.com

-megaresveratrol.net

-longevinex.com

For omega3s - Virgin or Rosita cod liver oil(includes preform vitamin A), Nordic Naturals

Another site no longer up also had a good supplement guide.  They distinguish between pharmaceutical grade and consumer grade

https://web.archive....plement-brands/

The supplement regimens listed on fastlifehacks.com tell us exactly what brands(at the bottom of each article) some online Nutritionists are taking

David SInclair

https://fastlifehack...utm_source=wppp

Rhonda Patrick

https://fastlifehack...pplements-list/

Peter Attia

https://fastlifehack...ia-supplements/

Andrew Huberman

https://fastlifehack...pplements-list/

What amazes me is the number of supplement companies that exist. It boggles my mind.

My favorites are (in no particular order:

Life Extension

Revgenetics

Terry Naturally

I have met or worked with the owners and other principles of these companies. Because of this, I am confident in their quality.

The best supplement company by a decent margin is Nootropics Depot.  Anyone who has spent time on the supplement/nootropic/biohacking communities on reddit will be aware that the owner has an absolutely intense dedication to quality, purity, and scientific development in every product they release.  

A number of other companies are also generally regarded as reputable, including Thorne, Life Extension, NOW, Doctor's Best (though they were bought by a Chinese company), Pure Encapsulations (though they were bought by Nestle), and a few others.