Hi Latex4life,
You are certainly down to “good vs good” options.
Although they are fairly similar … there are a few differences between them as well.
They use different covers (unquilted, wool quilting, or polyfoam quilting), have different layering (Spindle and Flexus have 3 layers and Arizona Premium has 2) and the Spindle mattress uses all continuous pour Dunlop in each layer (no Talalay) and the top layer is 3" instead of the 2" with the other two. They also have different return and exchange options and policies.
Having said that … when you are down to finalists that would all make great choices and there are no clear winners between them then which one of them would make the best final choice for your criteria and circumstances would depend on all the objective, subjective, and intangible parts of your personal value equation that are most important to you.
Your research has put you in a great position where none of them would be a “mistake” in terms of quality or value.
Phoenix