Hi Bunny1999,
I would consider all the suppliers in the list I linked earlier to be reliable suppliers.
I would first decide which type or blend of latex you think you would prefer (this is a preference choice). There is more about how Dunlop and Talalay compare in post #2 here. Once you have decided on the type and blend of latex you are most interested in then I would talk to the suppliers that sell that type and blend of latex on the telephone to help you decide on the firmness level that would have the best chance of success based on the “averages” of their customers that may be similar to you.
If you aren’t confident that a topper will be a good “match” for both you and the mattress you are using it on then I would also keep in mind that the exchange/return options may also be an important part of the “value” of a topper purchase just in case the topper you choose doesn’t turn out as well as you hoped for.
Phoenix