The best Netflix alternative depends on what you're looking for.
Netflix may have unlimited streaming for just $7.99, but its selection isn't great--unless you're a huge fan of Animal Planet documentaries and obscure indie films. Netflix's player is simple, though you can't pop the window out, and quality can be sketchy, depending on server traffic. Still, Netflix has nearly 20,000 titles on hand for streaming, and it's available on a wide variety of platforms.
Hulu Plus is the place to go if you're mainly concerned with keeping up-to-date on the latest TV shows. Movie selection, in contrast, is weak. Hulu Plus consistently has the best streaming quality and the largest number of shows available in HD, but it also has commercials, which it inflicts on paying subscribers. Hulu Plus is available on most popular platforms.
Blockbuster On Demand has good streaming quality, but its website needs a lot of work, and the selection isn't great. Blockbuster's new Movie Pass might be worth getting--too bad it's only available to Dish Network customers (for now).
iTunes isn't a streaming service at all, but it's worth checking out if you like to watch the latest releases. iTunes has almost every new release available for rental. However, if you want to watch more than a couple of movies a month, iTunes quickly gets expensive, since most titles cost between $2 and $4 each. iTunes rentals are available on PCs and Apple devices, but only Apple users can rent HD versions.
Amazon Prime streaming is still mostly a bonus service for people who want fast, free shipping. Selection is lacking, and video quality is poor. But with the addition of 2000 new Fox TV shows and movies, it may be worth checking out in a couple of months. It's the least expensive of the five services I looked at.
As for replacing the part of Netflix now known as Qwikster--good luck. Only Blockbuster currently operates a DVDs-by-mail service, called Blockbuster Total Access, and it starts at $9.99 per month, which is more expensive than Qwikster.
Blockbuster's Movie Pass currently exists only for Dish Network customers but should roll out to non-Dish customers in the future. It combines DVDs-by-mail and unlimited streaming. You can also try Redbox, but you'll have to pick up your DVDs at a Redbox station. and you'll be charged per night. Plus, Redbox stations can hold only so many DVDs--so it's a good idea to check your local Redbox online for the title you want before making the trip to the kiosk.