Hi MatrixClaw,
The first place I would start your research is the mattress shopping tutorial here which includes all the basic information, steps, and guidelines that can help you make the best possible choice … and more importantly know how and why to avoid the worst ones.
Two of the most important links in the tutorial that I would especially make sure you read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort” and PPP (Posture and alignment, Pressure relief, and Personal preferences) that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well you will sleep), durability (how long you will sleep well), and the overall value of a mattress compared to your other finalists (based on all the parts of your personal value equation that are most important to you).
I or some of the more knowledgeable or experienced members of the site can certainly help you to narrow down your options, help you focus on better quality/value choices that are available to you either locally or online, help you identify any lower quality materials or weak links in a mattress you may be considering, act as a fact check, answer many of the specific questions you may have along the way that don’t involve what you will “feel” on a mattress, and help with “how” to choose but only you can decide which specific mattress or combination of materials is the best match for you or which mattresses you are most interested in testing based on all the parts of your personal value equation that are most important to you.
Tuft & Needle is one of the members here which means that I think highly of them and I believe they compete well with the best in the industry in terms or their quality, value, service, and transparency. You can read more about “simplified choice” mattresses in post #1 of this topic and there is more information about Tuft & Needle and some of the other simplified choice mattresses in post #2 of the same topic.
In addition to the list of simplified choice mattresses … some of the better online options I’m aware of that are in lower budget ranges are listed in post #4 here.
You also have some very good local options available to you (including 4 of the members of this site) and the better options and possibilities I’m aware of in and around the Phoenix area which would also include Mesa, AZ (subject to making sure that any mattress you are considering meets the quality/value guidelines I linked earlier in this reply) are listed in post #4 here.
Phoenix