Hi bigredinmass,
You are in a similar position to others who have come to the site and need to exchange a mattress that they bought at a store where you are somewhat limited in terms of what you can exchange for. Post #66 here and the other posts it links to includes my comments to some other members in a similar position. The good news though is that from a quality perspective … Jordans has better options than the chain stores the other members were dealing with (where there isn’t a single mattress I would consider and they have to “make the best” of a bad situation) and at least you have some better quality options available to you … even if the value of what you bought and will probably need to exchange for is not the best available.
The first place I would start is the same place where people start when they are first looking for a new mattress and post #1 here which along with the information it links to will give you the basic information you need to eliminate the worst choices and focus on the better ones that are available to you. The same “rules” would apply for an exchange as for a new mattress purchase and the most important of them is to make sure you can find out the details of what is in a mattress you are considering. Jordans is at least more transparent with this type of information than most so you will be able to make meaningful quality and value comparisons between them.
In most cases … latex mattresses deserve the good reviews they receive but there are many differences between them and some “so called” latex mattresses have some weak links that shouldn’t be there IMO.
The PranaSleep are one of these. They are significantly overpriced and they also have thick layers of polyfoam on the sleeping surface which is much less durable than latex and will be the weak link in these mattresses. It’s not the latex in these that is the issue (it’s good quality) … it’s the polyfoam you would be sleeping on. You can see more about the Prana line in post #3 here.
The Simmons Natural Care also uses good quality materials in the comfort layers (which is typically where the weak link of a mattress is) and is a basic latex/polyfoam hybrid. The issue with these is not the quality of the materials they use but value because they are typically more than other similar mattresses made by smaller manufacturers. They also use slightly lower quality polyfoam in their support core than I would like to see (1.65 lb). Because you are probably locked in to a final purchase from Jordans … they may be among the better values there depending on the prices they charge (and of course on making sure you find out all the information about what is in each one you consder). They at least use good quality materials in the comfort layers which may make them one of your better options.
The quality and value of a mattress always depends on the specifics of what is in it. It’s always important to look at a mattress based on the contents and quality of material and never by brand even though it’s true that some manufacturers tend to use better quality materials in their mattresses. These are typically (but not always) smaller manufacturers that are sold either factory direct or through better sleep shops across the country.The Jordans brand mattresses may have some better value there because they make them themselves. A suitable mattress in the Jordan line may also make a good exchange option.
Unfortunately there is no “formula” that can translate your weight and height and sleeping position “specs” and turn it into a mattress design that is suitable for you. The only way to know this for certain is by local testing. As the link I provided earlier talks about … Comfort is mainly about pressure relief and you can test for this in a showroom. Support is mostly about alignment and you can also test for this in a showroom (although it’s more difficult). The third main part of buying a mattress though is knowing the quality of the materials in a specific mattress you are looking at because this determines whether the mattress has any weak links, its relative value compared to other mattresses, and whether it will maintain its comfort and support over the years. This is the part where knowing the quality specs is vital.
Because of all the variables involved … there is no way that someone else based on “theory at a distance” can know what may be comfortable for you but I can help you in terms of knowing whether a mattress that matches all your needs and preferences based on your testing (see post #46 here) has the quality that will have a better chance of maintaining the PPP (Pressure relief, Posture and alignment, and Personal preferences) that is the reason you bought it in the first place.
In the case of Jordans … I would tend to focus on and test their own mattresses and secondarily on the Natura and the Simmons Natural care line and exclude the rest of the manufacturers they carry.
As I mentioned earlier … you are more fortunate than many others who need to exchange a mattress and have purchased from a store or chain where there are no even reasonably good quality and value options to choose from 
Hope this helps
Phoenix