Columbia House has been around for a LONG time and there's a good reason for it: they have a huge selection and offer EXTREME discounts. If you're a heavy DVD consumer it's worth the membership.

I've purchased a few DVDs from DVD Empire and have never experienced any negatives.

Ah, Amazon.com! You really, really, really can't go wrong with Amazon.com. They are my first stop for DVDs or books and I'm always totally pleased with the service and delivery time. And you can't beat the fact that they offer you the option of purchasing lower priced used versions of what you're looking for if it's available.