I agree that the AA and RAC are probably still the best two, although I have used Green Flag and they were very good too.
The best way I've found to keep costs down (always have the full cover insurance) is to play them off against each other.
Year 1 - go to, say AA. Quote as a Newbie could be £80 (costs indicative)
Year 2 - AA renewal quote could be £140, so go to RAC as a Newbie for £80
Year 3 RAC renewal quote could be £140, so go to AA as a 'come back to us client' for £80
Year 4 - etc, etc, etc
It's worked for me