It took me a bit to track down this information as well so I wanted to post this here for people to stumble upon this thread later in time. As of posting these are the current best versions of restorations we have available to us. (Thanks ChainsawAsh for helping me get an understanding on all this)
2011 BluRay Versions OT and Prequels
Buy the BluRays and rip them to your computer. Super easy to get those.
Original Trilogy - Theatrical Versions*
There are various options for this. The 4k77 (4k80 yet to be released) and 4k83 are really good 35mm scans of the films in 4K. The Harmy’s Despecialized versions are really great too. Pick your poison. (*There is also the 1981 rerelease of Star Wars that added the Episode IV to the crawl. This version is available online as well as an offshoot version of Harmy’s Despecialized.)
1997 - Special Edition Trilogy
Harmy made a 720p “Respecialized Edition” for Star Wars. Adywan made a 1080p version of The Empire Strikes Back. The best currently available for Return of the Jedi are laserdisc rips.
2004 - DVD Trilogy Changes - OT and Prequels
Schorman’s HDTV Preservation is the best for HD versions of these.
Prequel Trilogy - Theatrical Versions
Episode I - Best we currently have are laserdisc rips.
Episode II - Best we have is a cam recording from a theater.
Episode III - Schorman did a really good restoration of this and it sounds like the new one in the works.
I’m not getting into the mess of audio mixes but from a visual standpoint these are the current releases. Thankfully a few projects are in the works to make the missing versions in HD. Hopefully in time we’ll have everything in HD. 😃 Lots of great projects around here.