For daily use at home, on a bed, I would favour wool blankets over any synthetic material. Warm, comfortable, not flammable.
Except for young children bed blankets need to be a generous size. As a minimum a full UK single size of 70 inches wide by 90 inches long. Bigger is better.
Synthetic bed blankets are IME less warm and are also uncomfortable as they trap moisture and produce an unpleasant sweaty or clammy feeling.
The best but still reasonably affordable wool bed blankets are made from 100% NEW wool and contain no recycled material.

For camping or outdoor activities, I would also favour wool for the same reasons as above, with the inherent fire resistance being of importance near camp fires.
Rough or outdoor use increases the chance of loss or damage and I would therefore favour the cheaper military type of wool blanket, these are often a bit smaller which keeps the cost down and reduces weight and bulk.

For blankets kept in a vehicle for emergencies any type will do, Comfort is secondary for short term emergency use.
Options include the very cheap part wool blankets made from recycled materials, as distributed by charities in disaster zones. Alternatively the cheap synthetic fleece blankets that are sold everywhere at low prices.
Or second-hand wool bed blankets as may be purchased very cheaply from charity shops.