Hi sucoast,
While choosing a topper that is the best match for both you and the mattress you are using it on (different mattresses can have a significant effect how a topper feels) can be tricky because there are so many unknowns and variables involved … post #2 here and the topper guidelines that it links to can help you use your own experience as a reference point for choosing a topper that has the best chance of success and also includes a link to the better topper sources I’m aware of.
In most cases … the members of the site only provide a discount and a referral fee on “mattress only” purchases and some of the topper sources that are listed aren’t members here at all so I would focus on making the best choice for you regardless of any other factors … although I do appreciate the thought 
Phoenix