I now use Greenflag and would recommend them over and above others. They 'guarantee' a 30 minute call out or your next year is half price. I have called them out twice, both were over the 30 minutes but within an hour, this year I have paid half price.
I used to be in the RAC for nearly 15 years, called them out twice in that period and both occasions were nearly 3 hours. The last one was on a Sunday in central London and they told me they were really busy, to which my reply was how can you be so busy on a Sunday in London, surely in the week your clients must be waiting all day if thats the case. I told them it was unacceptable, they were out in about 2 hours. I got out of the driver that they have a priority list, being a bloke on my own in a side street i was bottom of the waiting list, had i have been a single mother with small children blocking a main road they'd be out in 20 minutes. AA has a similar waiting list on breakdowns. Therefore generally as i drive on my own i thought it best to opt for Greenflags 30 minute guarantee system.
On both occasions they were great, the last one my clutch went, they organised a quote for me and offered to drop me at the garage, it was a bit too expensive so asked them to drop me home with the car about 5 miles away which they did no problem.