Hi tsakana,
You’ve probably already read this if you’ve read through the overviews but just in case … post #1 here has the basic information, steps and guidelines you will need to make good choices.
The first overview is perhaps the most important because it outlines the two basic functions of a mattress which is neutral alignment in all your sleeping positions and good pressure relief. These are always the goal of every mattress no matter what body type or sleeping positions someone may have.
You are much heavier than average which means that you will need firmer than average support and comfort layers in a mattress as well as more durable materials so that the more rapid softening and breakdown of the materials in your mattress doesn’t lead to the loss of comfort and support over a short period of time.
I would also focus on connecting with “experts” that have the knowledge and experience to provide you with good guidance about mattress materials and the type of designs that would be most suitable for you. They already know what you would otherwise need to learn and who you deal with can be one of the most important parts of successful mattress shopping.
Brooklyn Bedding is certainly one of the “best of the best” in the country in terms of the quality and value of their mattresses but quality and value are only part of the puzzle and the suitability of a mattress in terms of what I call PPP (Posture and alignment, Pressure relief, and Personal preferences) is just as important because no matter how good the quality or value of a mattress … if it’s not suitable for your body type and sleeping style then it would have little value to you.
You are fortunate to live in Phoenix because you have some of the best options in the country available to you and post #4 here includes the better choices I’m aware of in the Phoenix area (including 3 of the members of this site).
If you follow the steps one at a time you will greatly increase your odds of choosing a mattress that is the “best for you” and that meets all your needs, preferences, and criteria 
Phoenix