Generally for best quality (especially audio) you still need blu rays. There are some fancy specialty download services. But normal streaming from Amazon, Hulu, Netflix is pretty terrible. Apple and Disney are a little better but still way behind the blu ray.
How are you getting your surround sound?
I haven't paid attention to home theater in a long time so forgive me if this is a silly question. Is everyone still popping in a Blu-Ray disc to watch a movie if you're wanting to experience the latest in surround sound like Dolby Atmos, DTS, etc.? What are the ways you can get movies now with full audio formats encoded?