Aviva and Liberty always cheapest for me. Liberty lost me as a customer for life after fecking me around with the new car. Refused to quote me flat out unless I sent them proof of purchase etc and only then would they send it to a special panel to come up with a price. Can only imagine how high that would have been. Also wouldn't allow me to temporarily insure myself on the new car to take it home from England.
Cancelled my Liberty policy 10 months in. Took the hit of a year no claims. Went with Aviva then for €650 fully comp, full NCB protection. 27, full NCB, no points.