Rescuemycar.com was by far the cheapest, most comprehensive breakdown cover when I ran a comparison so when the company name popped up amongst the more reasonably priced for my car insurance I looked into it and decided to go with them. I added breakdown and got it cheaper too - bonus. Before my payment had even gone through online, a very friendly lady rang me to check that everything was ok and ask if I had any questions. Great service and attention.
The scary thing with insurance is that you don't really know how good a company is until you need them but I echo Jack's comment "Good so far" :)