Despite them being sourced from release prints rather than the negatives, 4K77 and its derivatives I think are the best quality sources for the OT until Lucasfilm comes out with from-scratch native 4K versions themselves. The blu-ray does at times have more detail due to being sourced from the negatives, but the scans themselves are just god-awful even before the 2004 coloring changes.
The Skymaster Edition is definitely the best I’ve ever seen SW/ANH ever look.