I've been using the free trials of all these companies providing DVD rentals by post. Quite a nice idea and if we watched more films, it would be worthwhile. As it is, I'm storing up movies to watch at leisure while these companies are in gold rush mode and offering unsustainable free offers.
Our of the three I've tried so far, I have to say that Blockbuster, the evil Amerikkkan multinational, have the best service. The range is far and away the best.
By way of example, neither of the others have Godard's classic Breathless, which I've been keen to watch for a long time, but Blockbuster has it. It's in the interest of these rental companies to have obscure films, because they're only likely to be of interest to a limited group but takes the heat off their high-demand blockbusters. And surely real film buffs are their target audience?