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
The Fifth Element. And I hope it stays tat way.
Coming this summer: Rob Schneider is the 6th Element!!