This thread was inspired by a post in the Plot Hole movie thread, in which a discussion about plot holes in the Back to the Future films led to fidstar-poker claiming that in any case, BTTF was still the GOAT trilogy. I responded that depending upon how you define trilogy for purposes of this discussion, I don't even think it would be in my top 5.
For example, I would consider The Good, The Bad, & The Ugly, along with Fistful of Dollars, and For A Few Dollars More, to be a movie trilogy even though it wasn't originally envisioned to be. In fact, some may consider that to be the GOAT movie trilogy.
I would also consider the original Star Wars movies, now labeled as Episodes IV-VI, as a better trilogy, even though there are now 8 (or 9 if you consider Rogue One).
I would also call Christopher Nolan's three Batman films a trilogy and would put that above BTTF.
Godfather I-III would also be in my top five, even though III came much later and wasn't nearly as good as the first two.
My final pick in my top 5 would be the Lord of the Rings trilogy. And there can be no argument at all as whether it counts as a trilogy considering all three parts were filmed at the same time and tell a continuing story.
And although I didn't include it in my top 5, I'm sure that there is at least one poster on this forum who would consider the original Bourne films as the GOAT trilogy, ainec.
So after posting my response, I thought that such a discussion might warrant its own thread rather than be lost at the bottom of the plot hole thread.
Anyone else want to weigh in with their Top Five?