Silentnight Airmax Mattress Topper

The Airmax is the value champion: a dual-layer hollowfibre topper (around 8cm) with mesh air borders that Silentnight says keep air moving to reduce overheating, for roughly £41 at king size (indicative). It is fully machine washable and treated to be anti-allergy, and it has amassed thousands of positive owner reviews. It ranks fourth because a soft-fibre filling cannot match the pressure relief or lasting support of foam or springs, and fibre toppers compress and flatten faster over time. But nothing else here comes close on price, and as a low-risk way to add a plush layer or freshen a firm bed it is the obvious budget choice. It carries a 2-year guarantee.