I've used EasyCinema for several years now, and remain very impressed. It's cheap, and it's pay-as-you-go, which means I don't have to worry about whether I'm watching enough films to make a monthly package sufficiently good value. Their database of films is huge (it's the same as that used by LoveFILM) so they almost always have the obscure film I want in stock. The web interface for selecting films is easy to use. I think that all films are the same price, regardless of popularity or recency. Occasionally I've had to reject a faulty disc, but the customer service has been prompt to send another. The discs always take a couple of days to arrive in the (second-class) post. Online film rentals don't have these particular problems, but then again, they are a little more expensive, and they don't tend to have quite as wide a range as EasyCinema has.