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I think they occupy fairly different niches, despite their similarity. Hulu is best for viewing current releases at your leisure, and it is the same price per month for Hulu Prime as it is for Netflix, so cost doesn't really enter into it for me. Amazon Prime is ok, but the selection is not as broad as Netflix, and it isn't available on all of the platforms that Hulu Plus and Netflix are, such as game consoles. Netflix is available on pretty much anything, has a wide variety of older movies/shows, along with a solid selection of foreign films.
For me, Netflix is still the winner, but I like foreign films, documentaries and classic films, so it fits me better than someone who likes to see the latest blockbuster films in their home soon after release. If you like broadcast TV shows, but don't have a DVR, Hulu would probably be better. If you like recent releases more, then you might want to consider Amazon Prime.