Hi Ivy76,
I would probably pay much more attention to your personal testing on different types of mattress than on the technical specifications of different materials and let your body tell you which mattress works best.
PPP (Posture and alignment, Pressure relief, and Personal preferences) is the single most important part of any mattress purchase because without this any mattress you purchase would have little value.
Outside of this it’s also important to make sure that the mattresses you like the best use high quality materials … especially in the comfort layers … so that you have some reasonable assurance that what you are buying will have a reasonable useful lifetime.
Outside of this … everything is less important and more of a preference issue than a “better worse” issue.
If you follow each step and the testing guidelines in the tutorial post here to the best or your ability then you will have less chance of being overwhelmed by mattress specs and “theory”.
You are fortunate to be in the Boston area where there are some very good options which are listed in post #2 here and post #2 here has some links with more feedback about many of them.
If you have read the tutorial post already … which step are you “stuck” on?
Phoenix