There's no one-size-fits-all answer! It depends on your sleeping position, body weight, and personal preference. Here's a general guide:
Side sleepers: Softer mattresses (plush or medium plush) cradle your shoulders and hips for pressure relief.
Back sleepers: Medium or medium-firm mattresses provide good spinal alignment and support.
Stomach sleepers: Firmer mattresses (firm or extra firm) keep your spine in a neutral position.
Combination sleepers: Opt for a medium or medium-firm mattress for a balance of support and comfort.