Hi nathanbgilliam,
In terms of a mattress … there is no “best” manufacturer but only the “best” design, materials, and layering for you and of course the “best” value based on all the many things that may be important to you in a mattress purchase based on your personal value equation. In other words … when it comes to individual preferences … each person may have a different opinion about what is “best” for them … and each may be very different.
Most of the latex that is used in mattresses comes from a few common suppliers (both Talalay and Dunlop) so from this perspective as well … it’s important to compare materials and design and how well each may fit your needs and preferences.
Whether you make a purchase online or locally … the steps would be the same and I believe that local testing is an important part of any mattress purchase whenever possible no matter where you end up making a purchase.
Post #1 here and the information, ideas, and guidelines it links to can help you discover which mattress, along with which manufacturer, or retailer is “best” for you 
If you let me know the city or zip code where you live I’d be happy to let you know about some of the better local options and possibilities I’m aware of (either for a purchase or for testing latex mattresses to use as a guideline or reference point for an online purchase)
Phoenix