Square/Rectangle Cushion Foam
Thin cushion foam for seating needs to be firm, so the 1", 1 1/2", 2" and 3" foam only comes that way.
For thicker cushions 4"-6", you may find the Medium feels more comfortable, but some people still prefer the Firm.
Better and Best quality has nothing to do with the Feel/Firmness. This has to do with longevity. For occasional use, choose Good (1.8 density); for daily use, choose Best (2.8 density).