Based on my own experiences and personal tastes these (not in any order) are my never again... And as we all can see, someone's hates are someone else's loves.
1.)
LeCellier- Loud, dark, cramped, rushed service, average quality meat, heavy sodium and mushroom risotto that tasted like Minute Rice with Campbells mushroom soup on it. LC for me is just an overall average at best experience. Can you tell this is not a favorite of mine.
I should say this place is not terrible, it's just that I expect so much more than this from a signature restaurant.
2.)
ABC Commissary- Went there the first time several years ago and it was so bad I threw it away and the waste can spit it back out at me.
The second time, just as miserable. I've heard some say it is better but I'm not about to get burned a third time.
3.
Pizzafari & Pizza Planet & and any other CS Pizza place in WDW - They are all your typical Digiorno or tombstone frozen pizza. Pick your poison, they are all the same. One and done for me.
4.
Chef Mickey- Not even average buffet quality food, loud, messy, buffet table poorly replenished and terrible service. Characters were fine but they couldn't save this place. I hear you can't mess up breakfast... Well they sure did for us.
5.
Cape May (dinner)- Below average buffet quality food, loud, anorexic and stringy crab legs, average service. The local Chinese buffet restaurant near me has the same quality crab legs. The rest of the buffet is Golden Coral quality.
6.
1900 PF (dinner) Below average buffet quality food, average service, poorly replenished, underwhelming selection. I fail to get all the rave for the strawberry soup. However Prince Charming, Cinderella, Lady Tremaine, Anastasia and Drizella were absolutely the most entertaining and hilarious characters I have encountered anywhere. They almost make up for the horrible food.
***NOTE***
I am pretty tough on my reviews of buffet restaurants. I really don't care much for them at all. They are usually mass produced food made for large quantities of people. It's more about quantity rather than quality. A couple of exceptions too this rule in my opinion are Boma (all meals), Biergarten (lunch/dinner) and the Wave (breakfast)... Those that fall into average buffets: Crystal Palace (breakfast) and Tusker House (breakfast).