Maybe I've just watched RedLetterMedia too much (and boy, I have), but I firmly believe that the quality of a movie of this kind, as such, is primarily decided by the characters, their arcs, and the structure of the story.
I realize movies can have other goodies worth watching (special effects, aesthetics, ideas, interesting plot, cool one-liners, whatever - the Nostalgia Critic likes Matrix Reloaded because... it doesn't focus on the characters he disliked anyway, but has lots of cool action and pseudo-philosophy), but if you just rate movies as a whole?
I mean, come on, people.
ROTJ may have a few scenes where Ford acts kinda weird, and have its weaker parts on Endor, but it still has a charismatic, strong protagonist with an effective arc and awesome climax, strong villains, genuine and entertaining characters, and overall strong emotional involvement.
ANH may not have the emotion, but all of the fun, character and structure.
Please, what does TPM have to be compared to that, in any way?
Not a single main character you can really identify with, or follow. Qui-Gon wants to train the boy, Obi-Wan wins the battle, Anakin the podrace. Padme wins her case.
All of these characters, a few moments and lines aside, range from boring and bland to annoying.
The story is an incoherent mess because it can't even establish the villains' motivations, or, I dunno, THE WHOLE POINT OF THE DAMN MOVIE.
The final duel may be epic, but in terms of character, it's earth and heaven when compared to ROTJ.
Sure, the movie's kinda fast-paced and fun at places, sometimes it even feels almost alive... and the same goes for II and III, but I maybe has the least of the "boring pretentious dialogue" stuff... but come on?
Just wondering whether the people giving the two movies the same (or almost) the same thing have actually thought things through. :)