Hi rgd53,
The first place I would start is post #1 here which has all the basic information, steps, and guidelines you will need to make the best possible choices.
The choice of materials and components in the comfort and support layers of a mattress is really a preference issue and there isn’t a “better or worse” choice. Regardless of which you prefer or the criteria that are most important to you though … it’s especially important to make sure that the materials and components are good quality because every type of material or component has better and worse quality versions. A mattress will tend to soften and break down from the top down so the quality of the materials in the upper layers especially is very important. In most cases … a mattress that has lost its comfort and/or support and needs to be replaced will still have support layers that are in good condition underneath the top comfort layers which have softened or broken down.
As you will see as you read the basic information I linked … I don’t recommend specific brands and going by brand is one of the worst ways to shop for a mattress (along with choosing a mattress based on its more subjective “showroom feel” or based on mattress reviews). A mattress is only as good as its construction and the quality of the materials inside it and knowing what is in a mattress is the only way to make informed choices no matter which manufacturer’s label is on the mattress. having said that … smaller independent manufacturers such as Jamison tend to use better quality materials and have better value than the major brands and are usually also more transparent about the materials in their mattresses so they would normally make better choices.
Some of the better options or possibilities in the Mobile area I’m aware of are listed in post #365 here.
If you follow the steps one by one you will be fine 
Phoenix