So, it seems that in movie trilogies, the third instalment often receives a fair bit of derision.
For example:
Star Wars VI, Spiderman 3, The Godfather Part III, X-men Last Stand, Terminator 3, and Aliens Cubed.
I’m not sure that this is always deserved. But rather than getting into the details of what goes wrong with the third instalment of an otherwise good series, I got to wondering, what franchises have reversed this trend.
What Part 3 movies were the best of the bunch?
Only one that comes to mind right now is Back to the Future III, which was the most enjoyable of the three (especially following on the heels of the rather messed-up Part II). I recently showed the whole trilogy to my kids and they absolutely loved Part III.
I too recently rewatched the whole trilogy with my kids, and all of us were pretty adamant that the first was, by far, the best of the lot.
I like the Bourne Ultimatum better than the first two Bourne movies. But that’s the only one I could come up with. Maybe Toy Story 3 or Return of the King, but normally by 3rd movies, the law of diminishing returns and a lack of freshness kicks in.
Perusing the list of 3rd movies on IMDB, I am struck by how few of them I’ve seen; usually, I’m done with a franchise by the end of the 2nd movie.
That said, I would say that Mad Max: Beyond Thunderdome was my favorite of the three.
Indiana Jones. The Last Crusade just edges out Raiders of the Lost Ark, and is far superior to both the lackluster Temple of Doom and the execrable Kingdom of the Crystal Skull.
Goldfinger is still the best of the Bonds.
Damn, I knew someone would beat me to it.
Personally I’ve always favoured Day of the Dead over the Night of the Living Dead and Dawn of the Dead.
I think Dawn of the Dead has some great ideas but the tone is uneven and the special effects (blue face paint!) aren’t always good enough. Day of the Dead is a smaller film but what it does it does very well.
TCMF-2L
Army of Darkness is the best of the Evil Dead movies.
I loved The Last Crusade. It’s my favorite of all the Indiana Jones’s
Plus I also like The Good, The Bad and the Ugly although I also like A Fistfull of Dollars and A Few Dollars More. All three are fine spaghetti westerns.
TCMF-2L
Damn, this was gonna be my pic. Here I was, scrolling down … no-one mentioned it so far … last post … damn! 
B]The Good, The Bad and the Ugly** is the best of the three (though all are good). The first is a Western reshoot of Yojimbo; the second is more original; but the third is a masterpiece.
Yeah, I could probably buy into that.
For me, it’s a toss-up between Indiana Jones 1 and 3. But I have to admit, it’s hard to beat the double bonus of River Phoenix and Sean Connery. And the boat chase! and the death traps!! And “You chose . . . poorly”!!!
Yep, you sold me. Part 3 is the best.
(Recently watched this series with the kids too. They loved them all (even 4), but their biggest reaction was to the first. They were amazed and delighted to see a movie so generous with action and adventure right from the get go.)
Have yet to see the Dollars trilogy, though I’ve got the first two on disc.
Must watch them when I’ve got the time.
(Already seen the spoilers in Back to the Future II and III.)
Prisoner of Azkaban is always watchable. Not quite as juvenile as the first two, and not yet all teen angsty. Frankly I live for seeing Hermione bounce Malfoy’s head off the rock when she clocks him.
Red is (almost universally regarded as) the best of Kieslowski’s Three Colors Trilogy, but they are all pretty great.
That’s the one that immediately came to mind, too. One of my friends has a yearly tradition–good God, it’s been over twenty years now–where he gets a bunch of people together on Ash Wednesday to binge watch the Evil Dead movies. 
The Return of the Pink Panther (1975) was viewed as a pretty good film, probably better than A Shot in the Dark, although I’m not sure it’s thought better than the original Pink Panther.
You have to ignore the 1968 film Inspector Clouseua to make this the third, but you can make a good case for it – that film didn’t have the same director, or Henry Mancini, or Peter Selers as Clouseau! (or any of the other recurring characters).
As a counter-example, I don’t think many people even remember Sidney Poitier’s film The Organization, the second sequel to In the Heat of the Night.
What, no love for A Very Harold & Kumar 3D Christmas? 
I make it a point to ignore STAR TREK: THE MOTION PICTURE, so as far as I’m concerned, THE VOYAGE HOME is the 3rd Trek flick, and it’s tied with KHAN as the best of the lot.