Hi teelobrown,
Welcome to the Mattress Forum! 
While I can’t help with “what” to choose, I certainly can help you with “how” to choose. The first thing to do would be to read 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 help you 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 (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).
After reading through the tutorial and moving on to investigating specific mattresses, you should always make sure that you find out information listed here so you can compare the quality of the materials and components to the durability guidelines here to make sure there are no lower quality materials or weak links in a mattress that would be a cause for concern relative to the durability and useful life of a mattress before making any purchase.
Latex can have an odor that some people describe as “vanilla-like” or “semi-sweet”. This generally dissipates rather quickly, but if you are sensitive to that odor then you certainly might wish to avoid that type of a product.
Memory foam is a temperature-sensitive material – the degree of which is determined by the foam manufacturer. The recent trend in memory foam has been toward less temperature sensitivity. Technically called visco-elastic foam, memory foam goes through a “transition” from elastic to viscous within a certain temperature range. In a cooler room, the foam will tend to feel a bit “stiffer”, and once it is warmed up from your body temperature it will soften. All memory foam will tend to be classified as “soft” (ILD ranges generally in 8-18, which can vary by testing protocols). No memory foam would be considered “supportive” or be appropriate for the support core of a mattress. So in general the support for your back will be reliant upon the layers of material beneath the upper memory foam layer.
While the choice of different types and combinations of materials and components or different types of mattresses (see this article) are more of a preference and a budget choice than a “better/worse” choice (as long as all the materials and components in a mattress are durable enough for your body type) … some people who prefer the slower response and more temperature sensitive “surface feel” of memory foam may prefer thinner layers of memory foam (usually in the 1" to 2" range) on top of more resilient materials to reduce the motion restriction that can come from sleeping or moving on thicker memory foam comfort layers. Other people may prefer the “feel” of using thinner layers of more resilient materials in the top layer (again usually in the 1" to 2" range") on top of thinner layers of memory foam underneath (also usually in the 1" to 2" range) which would provide a more resilient and less motion restricting “surface feel” that still has some of the slow response and gradual sinking in “feel” of the memory foam underneath it.
These different combinations of different types of foam materials with different properties in the comfort layers of a mattress will combine the properties and “feel” of both materials to different degrees depending on the specific materials, layer thickness, and properties of each material. The properties of materials and components that are closer to the top surface of a mattress will tend to have a bigger effect on the overall “feel” of a mattress than materials that are deeper in the mattress.
The only way to know for certain whether any specific combination of materials will be suitable for you or which ones you tend to prefer will be based on your own careful testing (hopefully using the testing guidelines in the tutorial) or your own personal sleeping experience because different people with different body types, sleeping styles, sensitivities, and circumstances can have very different experiences or opinions about whether the same mattress provides “enough” freedom of movement for their own personal preference, as there are many different combinations of memory foam and polyfoam that can achieve a softer surface comfort.
If you’re interested in looking online, then you may wish to use expertise of the members listed in post #21 here who are all very experienced and knowledgeable and specialize in providing the type of help and guidance on the phone that can help you make good choices. There are a wide range of memory foam options included in the choices there and I believe that all of them compete well with the best in the industry in terms of their quality, value, service, and transparency. Their detailed knowledge of their mattresses and how they fit with different body types and sleeping positions along with your feedback from local testing, a customer base of many people that they can use as reference points, and any exchange, return, or any options they have available to customize a mattress after a purchase can help lower the risk of an online purchase. These online retailers or manufacturers can also be a good “value reference” for local purchases to make sure that if you are paying a “premium” for a local purchase (in exchange for the kind of “in person” guidance, service, and value that comes with dealing with a local retailer that can help you make more “accurate” choices that you have tested in person) is not too high.
In addition to the online members of the site listed in the previous membership link … post #12 here has some of the better online memory foam options for those who are looking for a memory foam mattress.
If you’re interested in shopping locally, use the guidance in the mattress shopping tutorial to learn about the componentry within any mattress that you test in person to make sure that it contains durable and quality materials.
Post #2 here and this topic have more about the pros and cons of a local vs an online purchase.
I look forward to learning about your progress.
Phoenix