De'Longhi Dragon 4 (TRD41025T) 2.5kW Oil-Filled Radiator

The Dragon 4 is our best overall because it does the hardest job well: keeping a medium-to-large room (De'Longhi rates it for spaces up to around 75 cubic metres) at a stable temperature for long stretches. The sealed oil is never refilled — three heat settings up to 2500W warm the fins, and the thermostat cycles the element on and off to hold your set temperature, so it draws full power far less of the time than the wattage suggests. Against a ceramic fan heater like the Dreo, you give up instant warmth — an oil-filled radiator takes 15–20 minutes to come up to heat — but you gain silent running and residual warmth that lingers after the thermostat cuts out, which suits living rooms and bedrooms where you sit for hours. It is heavy and there is no app, but De'Longhi's build reputation is strong and some retailers list an extended manufacturer warranty of up to 10 years (registration usually required). At an indicative £130, it is the pick we would send most households to first.