Hi lotus65,
Part of the reason you will have so many different opinions about a topper is that nobody else can know for certain what type of topper will work best for you in combination with your mattress and your body type and sleeping positions. The same topper may work well on one mattress and not on another and for one person and not for another. In many cases it can involve some trial and error and making choices that have the “best odds” but just like anything else … “best odds” don’t always mean your choice will be successful.
Having said that … the topper guidelines here and the posts it links to have some guidelines that may be helpful in choosing a topper based on your experience on the mattress by itself and also includes some good sources for toppers.
If you are uncertain or have a history of multiple toppers that haven’t worked for you then it would be a good idea to take any return or exchange policies into account so that you still have options available if your topper/mattress combination isn’t a good match for you.
When you are a combination stomach/side sleeper it can be much more difficult to make a choice that is suitable for all your sleeping positions. Side sleepers need thicker/softer comfort layers to relieve pressure points but stomach sleeping is the most risky sleeping position and needs thinner and firmer comfort layers to prevent the pelvis from sinking in too far and sleeping in a swayback position. In these cases it’s generally best to have “just enough” thickness and softness in your mattress/topper combination to relieve pressure points on your side (and no more than absolutely necessary) so that there is less risk when you sleep on your stomach.
Your pillow may also be affecting you and stomach sleepers will generally be better with a much thinner pillow or no pillow at all. They can also benefit from using a thin pillow under their pelvis and lower abdomen when they are sleeping on their stomach.
A pillow that can be “scrunched” and made thicker or thinner can also be a good choice for people who sleep in multiple positions.
You can read more about the different types and blends of latex in post #6 here. Talalay and Dunlop have a different “feel” see post #7 here) and the choice between Talalay and Dunlop is mostly a preference choice rather than a “better/worse” choice.
Phoenix