I just go with the cheapest quote these days (of the same or better cover obviously and only with reputable companies). Each time I have rung to cancel the prior company, they have said that I should have rung them before cancelling. I told them that they should have sent me the best quote first time around! Strangely enough, it seems to drift between the Halifax and the RAC each year!
(69 year old, 9+ years no claims, ie zero claims, fully comp).