This thread is odd to me.

Isn't the idea of a 'perfect' film series, really just a way of saying 'Sequals are almost always not as good as the originals." In almost every case people mention here, they just eliminate the later entries in the series (with the exception of Temple of Doom).

Isn't that the nature of sequals; not to be as good as the original?

For the first movie in a series to be good enough to fully warrant a sequal, it almost by definition needs to push the boundaries of how much good story a certain concept can have, or else it will feel watered down and unimportant. Very few great films leave you feeling "Wow! That movie is sure open-ended!"

In the extremely rare cases of sequals that are highly respected (Bride of Frankenstein, ESB, Godfather II) they acheive that level by taking an original film that wasn't terribly deep character-wise, and exploring the all-ready beloved characters.

But usually a sequal is forced to find some way to dilute or reinterpret the original tale in order to continue it (Matrix, Highlander, Terminator). If not a diluted continuation the sequal either tries to go a different direction to mixed results (Temple of Doom, Back to the Future III, Futureworld) or is just a glorified remake (Rocky II-XXIII, ROTJ, the Jurassic Parks, French Connection II).

Oh yeah, and I love ROTJ.