Location improves the mail-rental experience. Well, mostly that's true.
The closer you are to a distribution center for any DVD-rental facility, you're generally better off. And none of them will tell you how close you are before you sign up and how likely you are to get 'overnight' mailings. And certainly none will tell you that they can elect to process your returns on THEIR schedule.
This Process Cycle is the time they receive the disk from you and the time it takes for them to refill your order.
NetFlix, I've found, has the best and most consistent processing. In most cases, this is a same-day operation. So if they retrieve your disks on Monday morning, they'll ship something out Monday evening. Some NetFlix customers have 3 full cycles a week (if they have a 3-out or 8-out subscription, they can get 3x3 or 3x8 titles a week - a LOT of movies).
Blockbuster generally spends 2 days and sometimes 3 for any one processing cycle to occur. They receive on Monday (they claim "in the afternoon") and don't send something out until Tuesday afternoon. And some users have noted that, with local deliveries, a SENT title is actually not posted by US MAIL until one day later as if Blockbuster claims a Sent Date well after that day's postal pickups occur. So it's not really mailed until the following day, but Blockbuster uses this SENT date claim to help with their stats.
Blockbuster offers 2 sometimes useful incentives: they generally have a few more classic film titles than NetFlix (compare title listings for "HOUDINI" between the two), although claiming to have them and actually delivering them seems to be a sticking point.
Blockbuster also has rental programs where you can exchange mail-order DVDs in a store and walk out with up to 5 in-store DVDs a month, free of charge. If you like a mix of old and new DVDs AND you live near a still-existing Blockbuster store, this is useful.
Blockbuster customers generally report a 2-full-cycle in any one week, but most only receive 1-full plus a partial (4 or 5 a week, on a 3-out-per-time subscription).
ClassicFlix.COM is a relative newcomer to this tango, operating only out of Oregon's mailing location so East Coasters should anticipate a 3-day mailing each way. ClassicFlix's same-day processing is claimed but not wholly supported - the complaints about their performance aren't nearly as legendary as Blockbuster's, at least.
ClassicFlix is probably considered a Only-Once-A-Week cycle processor for most of the country - if you have a 3-out subscription, you'll probably never get more than 3 in any week, no matter how prompt your viewing and mailing habits are.
ClassicFlix also offers a different variety of titles than these other chains do. Look up "VALENTINO" and you'll see the difference. Or compare their FILM NOIR sections.
ClassicFlix is the only facility that lists an accurate New Release Date with titles. NetFlix doesn't list New Releases weeks and months in advance - sometimes you can SEARCH for a upcoming release, and NetFlix may coincidentally acknowledge their plans to have it. But not always. Blockbuster does this even less.
I would recommend spending 4-5 months one service, and switch services and compare your totals and overall satisfaction. All of these services display a Next Payment Due Date on a user's profile, and a good Cancel Now actions so users can wait one day before Next Due Date and cancel without incurring additional credit card payments - as long as the disks are all returned.