Return of the Jedi. This isn't even a question.
Revenge of the Sith vs Rise of Skywalker is more fair
For me ROTJ.....then a huge gap, then ROS, then the Grand Canyon then ROTS.
I actually like ROTJ, sure it's not perfect but it does the job, and I actually cared about the characters. It provides a satisfying ending to the Star Wars trilogy and wraps up pretty much all the loose ends.
ROS ..... I didn't care whether Finn or Poe survived, they just had such little charm and chemistry. Chewbacca dies, and then before we have a moment to process it we find out he's still alive.
As for Rey, she was almost more of a plot device than a character in this film who manifests whatever force ability the story requires to move along - I mean the Dark Rey thing needed to last more than a few seconds to have an impact. The big problem with her character has always been that she has never felt like she's been challenged - hell she beat Kylo Ren in a lightsaber fight the first time she ever held a lightsaber. TLJ was probably her best movie because Luke made her think about stuff.
It takes 3 films for Luke Skywalker to grow from a whiny farm boy to a mature and competent Jedi- along the way he makes a bunch of mistakes, learns some hard lessons , nearly gets killed a few times, loses a hand and has his core beliefs shaken. When he stands over Darth Vader's burning corpse at the end of ROTJ we feel he's earned the victory.
I did like her visit to the moisture farm at the end of ROS and her commitment to continuing the Skywalker and Jedi legacy but if she had made a few more mistakes and maybe even a defeat along the way it would have made her a more relatable protagonist.
Carrie Fisher's scenes felt like some test footage picked up off the cutting room floor and shoehorned into the story for continuity's sake to fill in some gaps. A great gap to fill in would have been how Palpatine survived his fall into the reactor and then managed to build a fleet of ships ( which would have taken thousands of people to build and then crew, as well as vast amounts of material) on a planet that nobody knew the location of and only 2 Sith GPS devices could locate.
Kylo Ren probably has the best arc across the films but even he does a bunch of pointless stuff - like fix up his busted mask, which is significant because......who cares ? The knights of Ren are his posse, but dont really do much until he changes teams and needs to off them all. Also, the temper tantrums were just ridiculous.
What really kills any emotional engagement with ROS is how quickly the story leaps around - kind of the opposite problem that TLJ had, which really drags in parts.
Then there's Revenge of the Sith. The galactic civil war and birth of the Empire are the background with the real story being Anakin's incremental descent into darkness - a descent that is fully explained, the only problems being:
1) the explanation and the dialogue around it doesn't make a lot of sense ( " From my point of view the Jedi are evil!" shortly after murdering a room full of elementary school children ).
2) the actor who is entrusted with acting out this transformation has less talent than the 9 year old who played the same character as a child.
Hayden Christensen 's performance is so bad that we just don't care about Anakin's problems, in fact I couldn't wait to see Obi Wan mess him up at the end. The lightsaber fights had far too much useless twirling and spinning - something at ROS didn't do, thank goodness.
So Return of the Jedi easily takes this poll for me. I still rewatch it from time to time. I doubt I'll rewatch the other two anytime soon.