What is a good alternative to Gamefly?

I am sick and tired of wasting money on Gamefly for their extremely subpar low quality service (Extremely slow shipping, low game availability for popular titles that lasts for months, etc). Who else can I have games sent through the mail from? I used to use Blockbuster but I found much more of the same problem there since the amount of games available were always low and people with a pass never returned them and with only a half dozen copies or so it was hard to get a game.