Hi collation,
Making final choices can certainly be difficult but post #2 here may be helpful. It took me two weeks of hemming and hawing over smaller and smaller details to make my own final choice so you are certainly no different from many others who are choosing between “good and good” where there are no clear winners and the many objective, subjective, and intangible factors in any mattress purchase are unique to each person.
Higher density memory foam will be more durable up to about 6 lb density or so after which the extra durability of greater density is less but higher density memory foams are also more costly so of course there is always a tradeoff involved.
You are at the point where there are no “mistakes” in terms of quality/value which of course is the best place to be … even though I know it’s not easy to finally narrow things down to one 
Phoenix