With a number of options readily available, its not a question of which is the overall best, but which best suits you. Natural Filling; Goose & Duck Feather are popular and desirable fillings that provide a luxury feel. Being feather they offer a great deal of insulation / heat and are ideal for those that like the feeling of a weighted duvet. Allergy sufferers should be cautious if opting for Natural fillings. Microfibre Filling; Very tightly packed fibres that offer excellent warmth without excessive thickness. Although they can be manufactured relatively thin, they are a great all rounder being light, warm, and comfortable to sleep under. Hollowfibre Filling; A synthetic fibre that holds air between the fibres. With space between the fibres, it allows these to be breatheable, plump, light & comfortable. Hollowfibre is available is a number of quality levels. Please do look into the quality to ensure the duvet will last for many years, whilst maintaining its excellent properties. TOG RATING The TOG rating gives no indication of how heavy or thick a duvet will be, it purely offers information about how much insulation / heat retention it provides. The higher the TOG rating the warmer it is. Its worth remember that different fillings have different insulation properties, so a thinner & lighter duvet can potentially offer more warmth. 1 TOG 4.5 TOG Cool duvets that are ideal for warm Summer nights. 10.5 TOG 13.5 TOG Prominently used in the Spring & Autumn months where there may be a little chill in the air during the night. Although, some are more than satisfied to use these throughout the whole year. 15.5 TOG 16.5 TOG For those cold winter nights when you want to be snugged up, all warm & cosy.