I have recently bought and tried 3 types of memory foam mattress for extended periods of time. An £800 memory foam - way too soft, fits the body too well and I didn't feel supported. A £350 rest assured memory foam and pocket sprung base. A lot better than than the first but just doesn't feel right, firness I would say is medium. A £28 (not a typo) ebay memory foam jobbie brand new, I think it was from topsleep. It is very firm, very supportive and by far the best of the 3! Everyone is different but my wife used to suffer from very bad back problems which have totally disappeared.