Memory Foam Mattresses
Despite the name, a memory foam mattress is rarely made out of pure memory foam. That would not only be very expensive but also probably not very effective. A pure memory foam mattress would probably be too soft for many people.What Is A Memory Foam Mattress?
Most of the memory foam mattresses you can buy consist of a layer of memory foam on top of a supportive layer underneath. You can even buy some that are actually configurable with interchangeable support layers. This allows you to experiment to find the best option for you and also to review your needs at a later date.
Thickness and Density
The memory foam itself also comes in different densities - the higher densities usually being more expensive. Again, more is not always better. A very dense foam might be too firm for some people who would prefer the softer, lower densities.
As you might expect, the relative thicknesses and densities of the foam varies between different manufacturers. That affects the price and also how firm and supportive the mattress is - it's an important point of comparison between brands. Since everyone is different there is no "best" thickness.
It's a confusing market with so many combinations. As always the best option - if it's practical - is to try out the mattress yourself at a store before buying. You should also remember that when new memory foam does tend to emit an unpleasant chemical smell.
Toppers
If you already have a good quality mattress then an alternative might be to consider buying a memory foam topper (pad). This also gives more flexibility - if you decide you made the wrong choice of foam then you can just change the topper without having to change the entire matteress.
But even a luxury topper made from premium memory foam is unlikely to save an ancient, sagging mattress!