I believe that nobody knows how good their insurance company is until they have to make a claim.
I was so impressed with the way A.A. handled my claim that I decided I wanted to stay with them.
However, renewal quotes were too high so I did Compare the Market online, got good quotes from reliable providers like R.A.C., then made one phone call to A.A. to say that I was delighted with their service and wanted to stay with them, but, as a retired person could not afford the renewal quote. I told them what I could see online, and they did their best to match it. If they could not match it exactly price wise, they offered me an M and S voucher to make up the difference.
So, one search, one phone call, you can stay with your chosen provider.