Hi khaos,
Welcome to the site.
I’m not sure what you’ve read since you found the site but just in case you haven’t read it yet … the first place to 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 perhaps 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’ve 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 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’m not sure why you came to believe that the Tuft & Needle was a memory foam mattress but it doesn’t contain any memory foam.
Both the Aria and the Supreme are memory foam mattresses so outside of any differences in firmness both of them will have a different “feel” and slower response than the tuft & Needle which uses a more resilient high performance polyfoam in the comfort layers.
While I can certainly help with “how” to choose … It’s not possible to make specific suggestions or recommendations for either a mattress, manufacturers/retailers, or combinations of materials or components because 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”, firmness, or PPP (Posture and alignment, Pressure relief, and your own Personal preferences) or how a mattress will “feel” to you or compare to another mattress based on specs (either yours or a mattress), sleeping positions, health conditions, or “theory at a distance” that can possibly be more reliable than your own careful testing (hopefully using the testing guidelines in step 4 of the tutorial) or your own personal sleeping experience (see mattress firmness/comfort levels in post #2 here).
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 (and who won’t just sell you anything they can convince you to buy) 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 and firmness levels to different body types, sleeping positions, and preferences (or to other mattresses that they are familiar with) than anyone else.
If the only issue with a mattress is that it is too firm and there are no soft spots or sagging in the mattress then a good quality topper can certainly be an effective way to add some additional softness, “comfort” and pressure relief to your sleeping system but the only way to know for certain whether a specific mattress/topper combination is a good “match” for both of you in terms of comfort, firmness, and PPP is based on your own careful testing or personal experience on the combination. If you can’t test the combination in person then there will always be always some risk and uncertainty involved in adding a topper because the specifics of the mattress itself along with your own body type, sleeping position, and preferences can affect which specific topper would be a suitable choice on any specific mattress.
There is more information about choosing a topper and a link to the better online sources I’m aware of in post #2 here and the topper guidelines it links to which along with a conversation with a reliable and knowledgeable supplier (that can provide you with good information about how their toppers compare to each other or to other toppers they are familiar with that are available on the market) can help you use your sleeping experience as a reference point and guideline to help you choose the type, thickness, and firmness for a topper that has the least possible risk and the best chance for success.
Because of the uncertainty that can be involved with purchasing a topper where you can’t test the combination in person … a good exchange/return policy can also reduce the risk of an online topper purchase so I would make sure you are comfortable with the options you have available after a purchase and any costs involved just in case the topper you choose doesn’t turn out as well as you hoped for.
I’m guessing that the list you saw was the one in post #2 here. The only recommended store on the list is Magic Sleeper who is a member of the site and the others are “possibilities” that would depend on confirming that they are completely transparent about the type and quality of the materials in their mattresses (see this article) although I do know that Denver mattress does disclose all the information that you would need to make an informed choice. Of course I would also make sure that any specific mattress you are considering meets the quality/value guidelines I linked earlier in this reply.
I don’t keep a record of the individual mattresses or their specs that the retailers and manufacturers in the hundreds of forum lists throughout the forum carry on their floor or have available online (it would be a bigger job than anyone could keep up with in a constantly changing market) but checking their websites and making some preliminary phone calls to the retailers/manufacturers that are on the local or online lists is always a good idea before you decide on which retailers or manufacturers you wish to deal with anyway. This will tell you which of them carry mattresses that would meet your specific criteria, are transparent about the materials in their mattresses, and that carry the type of mattresses that you are interested in that are also in the budget range you are comfortable with. Once you have checked their websites and/or talked with the ones that interest you then you will be in a much better position to decide on the ones that you are most interested in considering or visiting based on the results of your preliminary research and conversations.
Again the best source of guidance about the Dreamfoam mattresses would be a more detailed phone conversation to Dreamfoam.
Any particular online mattresses may be a “great” match for a relatively small percentage of people, a good match for a larger percentage, and an "OK match for a larger percentage yet, but for those where it isn’t a “good enough” match then most people would just return the mattress and try a different one unless there are other options that the company has available that don’t involve additional expense.
If you do decide to add the topper I would make sure you are comfortable with the additional cost of your “sleeping system” compared to other mattresses that are available to you that may not need a topper and I would also make sure that you are comfortable with the options you have after a purchase if the topper doesn’t work out as well as you hoped for and you need to return both the mattress and the topper.
I or some of the more knowledgeable members of the site can 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, 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, manufacturer, or combination of materials is “best for you” regardless of the name of the manufacturer on the label or whether anyone else would have the same criteria or circumstances or would make the same choice.
Phoenix