What stand alone movie was so good that you think a sequel would ruin it?

Cast Away with Tom Hanks there's nothing else to be said in that movie. I just want to know what was in the package. What if it was a solar powered cellphone and he could have made a call and been rescued years ago lol

Clerks.

Due date

Mad Mad Mad Mad World great stars lots of funny stuff a sequel wouldnt come close, Caddyshack was great the sequel made me gag!!

You have my first choice.

Usual Suspects

Highlander. There can be only one and there should have been only one.

Boondock saints was good .. the 2nd one was a wannabe with too much cussing and no point.. unlike the original

Avatar. They DID a sequel...and it flopped.

The Accountant 2 dragged the Accountant 1 way down. They seriously should have done a much better job on the sequel.

Pet Sematary