I would think:
-Star Wars (original cut)
-Empire Strikes Back (original cut)
-Return of the Jedi (original cut)
-Caravan of Courage
-Battle for Endor
-The Force Awakens
If you wanted to do an alternate-quality marathon, you could try:
-The Phantom Menace
-Attack of the Clones
-Revenge of the Sith
-The Holiday Special
Each set you’ll notice has its own flavor. Namely, one set is good and another is not so good, or rather, bad.