What I have noticed about the Laserdisc audio in many films is that the sound is very in-depth and robust.
Which Original Trilogy preservation do you recommend?
Depends on what you want. If you want the experience of watching the movies in a theater, go for the 4Kxx projects. If you want to see what a respectful Blu-ray release would have looked like, Despecialized is your best bet IMO. I lean toward the latter. Star Wars is sadly in the roughest shape of the trilogy for both projects.