A 4K Blu-ray will look significantly better than streaming in 4K. Streaming has an advantage that (sometimes, on newer hardware) it can use newer / better video codecs than DVD/Blu-ray/4k Blu-ray, which are frozen in time at a specific standard for decoding. However, Blu-rays can store 100GB of data. The massive increase in bitrate more than makes up the difference.
When downloading video, you can grab a remux (the raw video files off of the disk, just stripped of DRM), or a re-encode (those video files compressed again using a better codec). A re-encode will be about the same size as a streaming release and generally has higher quality. Re-encodes tend to use cutting-edge video compression, and pirates are willing to throw more compute time at a single output format than a streaming service which has to produce video files for many target devices.
A 4K Blu-ray (or remux) will get you the best quality, followed by re-encodes, and then web-dl's.
When downloading video, you can grab a remux (the raw video files off of the disk, just stripped of DRM), or a re-encode (those video files compressed again using a better codec). A re-encode will be about the same size as a streaming release and generally has higher quality. Re-encodes tend to use cutting-edge video compression, and pirates are willing to throw more compute time at a single output format than a streaming service which has to produce video files for many target devices.
A 4K Blu-ray (or remux) will get you the best quality, followed by re-encodes, and then web-dl's.