Hi ElizabethKing,
While I can’t speak to which of the mattresses you are considering would be the best “match” for you in terms of comfort or PPP or which one you would sleep best on … you are certainly looking as some great quality/value choices and all of them use high quality and durable materials and there aren’t any lower quality materials or weak links in any of them.
As you also know they are also all members of this site which means that I think very highly of them and I believe they all compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency.
The Spindle mattress uses three 3" layers of 100% natural Continuous pour Dunlop latex and has an organic cotton cover quilted with natural wool.
The the Foam Sweet Foam Urban Green 9" mattress uses three 3" layers that give you a choice between certified organic Dunlop or 100% natural Talalay in each of the layers.
The Cozy Pure Natural Comfort 9" mattress uses a 6" support core of 100% natural Dunlop and has a 2" sculpted comfort layer that is also made from 100% natural Dunlop (their organic comfort zone mattresses use 100% natural Dunlop that is also certified organic) and also has an organic cotton cover quilted with natural wool.
The choice between different types and blends of latex is always a preference choice rather than a “better/worse” choice and there is more about the different types and blends of latex in post #6 here.
All the latex you are likely to encounter (Dunlop or Talalay made with either natural or synthetic rubber or a blend of both) will have been certified by either Oeko-Tex or Eco-Institut for harmful substances and VOC’s (see post #2 here) and I would consider any type or blend of latex to be a very “safe” material in terms of harmful substances and VOC’s.
There is also more about the benefits of an organic certification in post #3 here and there is more about the different levels of organic certifications in post #2 here and about organic and safety certifications in general in post #2 here for those where an organic certification is important for personal, environmental, or lifestyle reasons (although the organic certification won’t affect the safety, quality, or durability of the latex).
The thickness of a mattress or of individual layers is really just a side effect of the design and by itself isn’t particularly meaningful (see post #2 here). In some cases higher weight ranges will sometimes do better with a mattress that is a little thicker than lower weight ranges but even this depends more on the specific design and combination of materials in the mattress and on how well the mattress “as a whole” matches your specific needs and preferences than anything else.
Each of the manufacturers you are considering also has different options available after a purchase as well that can allow you to “fine tune” your choice or to return or exchange individual layers or the mattress as well so I would make sure you are comfortable with the options you have available after a purchase that are “built in” to the cost of each of their mattresses since this can also be an important part of the “value” of a mattress purchase.
There is also more about the 3 most important parts of “value” of a mattress purchase in post #13 here 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 suitability, durability, and all the other parts of your personal value equation that are most important to you).
I would keep in mind that the first “rule” of mattress shopping is to always remember that you are the only one that can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved that are unique to each person to use a formula or for anyone to be able to predict or make a specific suggestion or recommendation about which mattress or combination of materials and components or which type of mattress would be the best “match” for you in terms of “comfort” or PPP (Posture and alignment, Pressure relief, and Personal preferences) or how a mattress will “feel” to you or compare to another mattress based on specs (either yours or a mattress) or “theory at a distance” that can possibly be more accurate than your own careful testing (hopefully using the testing guidelines in step 4 of the tutorial) or if you can’t test a mattress in person then your own personal sleeping experience (see mattress firmness/comfort levels in post #2 here).
Having said that … when you can’t test a mattress in person then the most reliable source of guidance is always a more detailed phone conversation with a knowledgeable and experienced retailer or manufacturer that has your best interests at heart (which would certainly include all the manufacturers you are considering) and who can help “talk you through” the specifics of their mattresses and the properties and “feel” of the materials they are using (fast or slow response, resilience, firmness etc) and the options they have available that may be the best “match” for you based on the information you provide them, any local testing you have done or mattresses you have slept on and liked or other mattresses you are considering that they are familiar with, and the “averages” of other customers that are similar to you. They will know more about “matching” their specific mattress designs to different body types, sleeping positions, and preferences (or to other mattresses that they are familiar with) than anyone else.
Once you are down to a list of finalists and you are confident that they would all be a good match for you in terms of PPP (or you have good options after a purchase if you aren’t) and that there are no lower quality materials or weak links in any of them in terms of durability (which there aren’t) then you would be down to finalists that are comparing “good to good”. If there are no clear winners between them at this point (which is usually a good indication that you have done some very good research) then you are in the fortunate position that any of them would likely make a good quality/value choice and (post #2 here) can help you make a final choice based on your local testing or mattresses you have slept well on, your more detailed conversations with each of them, your confidence about PPP and the suitability of each one, their prices, your preferences, the options you have after a purchase to fine tune the mattress or exchange or return the mattress or individual layers, any additional “value” extras that are part of each purchase, and on “informed best judgement” based on all the other objective, subjective, and intangible parts of your personal value equation that are most important to you. Sometimes a final choice may even come down to very minor differences or can sometimes just be a matter of “gut feel” or “educated best judgement”.
Phoenix