The first that comes to mind for me is The Breakfast Club and I hope it never does have a sequel or remake
The Princess Bride is another good one
Edit: another one of my favourites is Wall.E, my favourite Pixar movie. There are also several other Pixar movies that don’t have sequels or remakes yet
Titanic
How they going to bring the iceberg back? That bad boy is melted for sure.
Does have a sequel:
Ah, Asylum Films, never change
🎶 my heart will go on! 🎶
Elderly Rose as she jumps off the ship: lol, not fucking likely!