How to buy a mattress
This article describes has tips on how to pick a mattress that meets your preferences.
A good soft mattress should feel luxurious, deep and evenly supportive. Most soft mattresses are at least 15 or 20cm thick.
The surface of a good soft mattress will contour deeply and evenly around the body.
Most people like medium density mattresses. A good medium will balance moderate contouring with weight support.
The surface of the mattress should contour smoothly around the body but without sinking in too much. If you feel a bump when you bounce your hips, or a tough spot when you wriggle your shoulders, then you may need a thicker mattress in a medium.
Firm mattresses should provide even and contouring weight distribution.
Avoid firm mattresses that feel tough like boards on springs'. A good firm mattress will have minimal 'sink in' but should still feel responsive.
There is no perfect, "one-size-fits-all" mattress. It all depends on your body and your preferences.