I honestly thought this was going to be about game streaming when I clicked, and since I don't (yet) see anything specifically excluding them, I'm going to go ahead and continue with my response.
I tend to prefer Twitch. Not necessarily because it's fantastic, more because it's the most functional and least buggy with what I would consider in regard to absolute basic levels of service. They have an option for automagically uploading streamed content to Youtube, which seems like it would be an obvious feature, but not all streaming sites have implemented this. I also prefer them because their VODs don't suffer from an A/V desynchronization issue like another of the larger streaming services I've tried.
For movies and similar, I haven't purchased anything from streaming sites because the quality is always inferior to disc. I don't fault anyone for doing so, I understand how people like the convenience, it's just not something I need. I don't buy that many movies or shows to begin with, and the ones I do are things I want to own in the highest quality available to me.
I actually do like Twitch, as well. I also use that one. Personally, while I use a lot of streaming sites, I don't think I've ever bought them from the site. That makes me think more of YouTube and certain movies on Amazon Prime. ---
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