We have cover thru Direct Line as they do my wife's car insurance, so we got a good deal ... I just put some invented details for you thru their online quote system and got £33 from them for their most basic package, so that puts them on a par with the RAC.
If you want to get a proper quote based on your true details, go to
http://uk.directline.com/rescue/welcome.htm
I had RAC cover personally from when I first moved away from home to Uni and realised I couldn't just phone my dad if I broke down, until I sold my last private car and got a company one; now I have RAC cover through the company. I've had them out at least half a dozen times over the last 12 years and each time bar one they've been great, if a little slow once or twice.
The only real problem was the first time, while I was away at Uni in the sleepy rural West Wales town of Lampeter. The car just wouldn't start; it turned out eventually to be a blown fuse but the RAC man 'checked' the fusebox and didn't spot it (he apparently misread the fuse diagram and checked the spares rather than any of the live ones). He determined that it was the elctronic ignition unit and was on the point of asking me to run round some of the local garages asking for helop when he decided to check the fuses again, this time spotting the error. Problem fixed, after waiting an hour for him to turn up and 45 minutes in the rain for him to arrive at a solution. I think the real problem here was that the local RAC man was more used to fixing the battered 20-year-old land rovers and Nissan Sunnies that live in muddy farmyards than relatively new Rover Metros.
Despite all this I would totally recommend them. Any car of any age can have a serious breakdown and a tow over any distance can be expensive. I had a recovery back to the Wirral from Birmingham once, which didn't cost me a penny as it was covered by my RAC membership.