If you really want to try a bad movie.
Go for The Room.
<a href="https://www.vox.com/culture/2017/12/2/16720012/the-room-tommy-wiseau-backstory-explained" style="background-color: rgb(255, 255, 255);">https://www.vox.com/culture/2017/12/2/16720012/the-room-tommy-wiseau-backstory-explained</a>
If you want to see a bad movie, I'd recommend Attack of the Killer Tomatoes. Don't say I didn't warn you....
https://en.wikipedia.org/wiki/Attack_of_the_Killer_Tomatoes
I can't really say what is best because I have seen a lot of good films.
But I can say that the worst film for me is Vanilla Sky, the Tom Cruise, and Penelope Cruz movie.
the best movies are "Miss Baek" and "Battleship Island" these are Korean movies and i'm in love with them especially Miss Baek <3 :) however, i'm not sure about worst movie because i always pick a up a good movie to watch ^^