Probably in no order:
1. A Pixar film. I dunno which, there's just too much to choose from!
2. Wreck it Ralph
3. Shrek 2
4. Birdemic (it's hilariously bad. LOL special effects. LOL wooden planks masquerading as actors. LOL special effects. LOL sound editing. LOL plot. LOL special effects. LOL Rifftrax.)
5. Manos: The Hands of Fate (MST3K's high point)
6. Plan 9 from Outer Space (oh Ed Wood, you're so funny and your movies are so bad it's funny)
7. The Room (Tommy Wiseau's masterpiece of a bad film)
8. Lord of the Rings (funny if watched with Rifftrax)
9. Rio (like animated birds)
10.....I guess Santa and the Ice Cream Bunny Rifftrax?
That was pretty tough for me to list since I don't watch movies often. TV and movies just aren't my cup of tea.
And some of my least favorites as a bonus (also in no order)
1. The Last Airbender (M. Shamalyan really butchered this)
2. Bayformers The Trilogy (aka Micheal Bay Transformers movies)
3. Epic Movie, Date Movie, Scary Movie, Disaster Movie, Whatever Movie
4. Monster A Go-Go (painful to watch, even with MST3K)
5. Star Wars: Episode 1 (because lengthy conversations about the government diplomacy is fun to watch. Also, Jar Jar)
6. Garbage Pail Kids (eewwwww)
7. Super Mario Bros. (why? WHYYY?)
8. Superbabies 2
9. Both the awful Italian Titanic copyright infringers and rip-offs aka movies (Titanic: The Legend Goes On.... and The Legend of the Titanic) and did I mention one of them contains a rapping dog?
10. Son of the Mask (disturbing imagery)