Hi Stef1999,
As you can see in these guidelines … Tempurpedic and Serta are manufacturers I wouldn’t consider but Select Foam / Brickell Mattress is one of the members of this site and they are completely transparent about the quality of the materials they use. You are fortunate to be able to test them in person because they are usually sold online. They have them set up in their store along with the Tempurpedic lineup (and some super premium brands as well) so you can compare them side by side and they are certainly good quality and value.
Post #1 here has some of the basic information steps and guidelines that may be helpful (including some suggestions about testing mattresses) and some of the other options or possibilities in the Miami area are listed in post #2 here.
Phoenix