Which are the top auto insurance companies in the UK?

There are a lot of companies in the UK offering car insurance which is a good thing for the consumer as lots of competition means lower prices and hopefully better value and service ,the ones that instantly spring to mind are direct line Admiral MoreThan and Churchill who seem to be constantly advertising on the TV the of course there is The AA and The RAC the mayor supermarkets like Tesco Sainsbury's and Marks and Spencer also offer this service.