The biggest reason why I avoid Blockbuster with extreme prejudice is because they edit some of the movies that they carry without making it obvious to their customers. Perhaps there's a disclaimer somewhere, but I've never found it. I first noticed this while watching a Blockbuster-rented copy of "The Toxic Avenger," which I'd seen a few times in years past. With the Blockbuster copy, a couple of the really memorable, gory shots were just NOT THERE. It was still rated R, but it was missing some footage that some executive must have found offensive. I later noticed similar edits in other movies.
If Blockbuster's gonna manipulate their movies without making it obvious to the customers, then screw 'em. (And sure, WalMart does the same thing, but I don't shop at WalMart, either. Netflix, as far as I know, doesn't engage in such censorship.)