Hi pglover,
Unfortunately there isn’t a formula that can choose a mattress based on specs alone. There are just too many variables to be able to do this for any specific person.
When you are choosing a mattress online … one of the most important parts of 'value" is your confidence in how well it will match your needs and preferences. Regardless of the initial “commodity value” of a mattress … the most important part of value is how well you sleep on it over the years. When you are looking back at a mattress purchase 5 or 10 years down the road … the quality of your sleep will be much more important to you than just the price you paid for the mattress. Of course the “commodity value” is an important part of any purchase but it’s only part of the picture.
If you are looking at an online purchase … I would include several factors in your evaluations so that you can determine the “range” of prices that the purchase may end up costing you.
The first of these is the best case and the bottom of the range which of course is what will this cost me if the mattress turns out to be perfect the first time.
I would also calculate the cost of the options I would have if I made the wrong comfort choice and the mattress doesn’t initially match my needs and preferences. Depending on the merchant and the options they offer this could involve a layer exchange, a mattress exchange, an additional purchase of a topper or other components, or in the worst case the return of the mattress itself if there is a refund policy or selling the mattress and starting all over again if there is no refund policy. Of course all of these are not options with every purchase so you would need to include the cost of a “mistake” that is specific to each merchant with any online purchase and factor that into your price range, expectations, and your risk tolerance. I would at least factor in the cost of making some kind of adjustment as part of the price range that the purchase may end up costing you and to evaluate any risk involved with the purchase. The more local testing you do on mattresses that are similar to the online purchase you are considering the more likely it is that you will make the most suitable initial choice. All of this is part of value.
As you can see from post #46 here as well … value has many other components besides just the raw material cost of a mattress and in many cases this can also be difficult to assess because while it may be easier to evaluate the relative value of any foam materials in a mattress if you know the details of the material … the foam alone is not the entire mattress and the ticking and quilting as well as the benefits of working with a particular retailer or manufacturer can also be a significant part of the cost and value of a mattress and this is more difficult to compare. Post #4 here along with post #2 here would also be well worth reading.
In terms of your comparisons between the Dreamfoam options … post #2 here has my thoughts about an all latex mattress (such as their Total Latex mattress) vs a polyfoam/latex hybrid (such as the Ultra Plush or the Eurotop). Post #2 here has more about the benefits and advantages of the Eurotop with the exchangeable layer vs the Ultimate Dreams Ultra plush. The goal is to know the advantages and disadvantages of each so each person can decide which best meets their personal value equation and risk tolerance.
The Cozypure mattresses use exceptionally high quality materials and components and Cheryl pays strict attention to every component down to the type of thread they use. Some of their components (such as the Lanoodle topper) are unique and there is little to compare them to in practical terms. From a commodity perspective alone they my not in the same value range as other choices but the the “value” of Cozy Pure is just as much in the many other benefits they offer (see post #11 here) which may be an even more important part of someone’s value equation besides just the commodity value of a mattress or component itself. Like the other members here … they are among the “best or the best” but their value" would be more attractive to consumers that measured value in different ways than just price alone.
As you can see … once you are down to final choices and have eliminated all the worst choices … my role is always to help people decide “how” to choose based on their own personal value equation (no matter how they may define it) … rather than tell them “what” to choose. Value is always relative to what is most important to each person.
It’s always great when your final choices are all good ones and strictly a matter of personal preferences and when no matter which direction you choose it would be difficult to make a “bad” choice 
Phoenix