I love Netflix. As a fan of "B-movies" (primarily horror, but also some sci-fi), I find Netflix's selection incredible.
I have had one selection not ship due to being out of stock, but out of so far 40 movies, that's not bad at all...and the price for the 3-in-1 package is cheaper than renting one a week at blockbuster (I tend to end up with 3 a week, with how I am slackish in sending them back).
I haven't been that big of a blockbuster fan after they dedicated half their store to videogames and selling movies, and not renting movies. Hollywood video is OK, but the one near my place seems to have too many beat up discs for my liking.
So Netflix wins!