Hiya
Agreed value, for starters. Plus you tend to be dealing with people who understand your attachment to your car and aren't just looking for the cheapest repairer if the worst happens.
You usually have to agree to garage the car overnight at your home address and it really only suits if you are happy to limit mileage. You don't need a no-claims bonus either
The price is generally much cheaper as they work on the basis the car is generally treated better than your spouse