In the case of books, I generally link to the Hardcover edition and in the case of movies, to the DVD edition. However, Amazon generally provides easy links to all their other editions. I link to these editions because I personally prefer them, not because I wish to encourage you to buy a more expensive version. Make certain you are buying the edition you want.
These links are offered for two reason. 1) So if you want something you can easily find it. 2) So I might make a few bucks without costing you anything to help defer the time and expenses of maintaining the site. Don't buy anything you don't really want.