Hi jeanneny,
The first place to start your research is the mattress shopping tutorial here which includes all the basic information, steps, and guidelines that you will need to make the best possible choice … and 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 that is the best “match” for you in terms of 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 that are involved in each of them 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, durability, and value.
There is more about the many variables that can affect sleeping temperature in post #2 here that can help you choose a choose the combination of materials and components and the types of mattresses that will have the best chance of keeping you in a temperature range that you are comfortable with.
There are three main types of foam materials (memory foam, polyfoam, latex foam) and in very general terms memory foam tends to sleep warmer than polyfoam which in turn tends to sleep warmer than latex although there are many other variables involved in sleeping temperature as well besides just the type of foam material that you are sleeping on.
A mattress that sleeps warm for some people may be well inside a comfortable temperature range for others depending on where they are in the “oven to iceberg” range and on the temperature and humidity in their bedroom and the mattress protector or any mattress pad you are using, your sheets and bedding, and your bedclothes, which can all have a significant effect on sleeping temperature regardless of your mattress and in some cases changing these may be all that is necessary to keep sleeping temperatures inside the range that you are comfortable with even if one mattress tends to sleep warmer than another.
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 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 would be the best “match” for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) based on specs (either yours or a mattress) or “theory at a distance” that can possibly be more accurate than your own careful testing or personal experience … hopefully using the testing guidelines in the tutorial post (see mattress firmness/comfort levels in post #2 here).
A pillowtop is a type of mattress that has a separate “pillow” that is sewn to a mattress with recessed edges (like this) and is just a method of construction that allows the top layer in the “pillow” to respond more independently than it would if the same layer was inside the main mattress cover. The problem with most pillowtops that are sold by the major brands or in the mainstream industry isn’t so much the pillowtop design itself as the quality/density and durability of the materials inside it because pillowtops that use lower quality materials in the mattress or the pillowtop will tend to develop soft spots and premature impressions much more quickly. Other than the quality and durability of the materials there is nothing about a pillowtop that would make it inherently better or worse than any other type of mattress. It would all depend on which type of mattress your careful testing indicated is the best “match” for you in terms of PPP.
Brand shopping can also be among the most risky ways to choose a mattress because you are buying a specific mattress not the brand and all manufacturers have access to the same or similar components and materials. Most of the most heavily advertised and most commonly available brands that you would recognize are the ones I would avoid anyway (see the guidelines here) and many of the better manufacturers are smaller and are only available locally or regionally. The name of the manufacturer on the label also won’t tell you anything about whether a specific mattress is suitable for you in terms of PPP or whether there are any lower quality materials or weak links in the design. There is more about the risks of brand shopping in post #5 here and post #12 here).
The better options or possibilities I’m aware of in the Rochester, NY area (subject to the quality/value guidelines I linked earlier in this reply) are listed in post #11 here.
Phoenix