In addition to people having different/individual tastes, I think you have to consider "factor x"!!
"Factor x" is that unknown - change of chef, wait staff having a bad day, unexpected guest #s (high or low), etc, etc, etc.
We really disliked our meal at Chef Mickey's. The food was dried out & generally lousy - buffet or not, there was little to recommend it. That's the only meal I can think of that we've ever disliked the food.
As far as service & other problems.....Backyard BBQ & Rainforest come to mind.
I think, though, that with Rainforest you need to keep in mind that it isn't "Disney" and doesn't seem to have the same standards re: service. Our lunch took longer than ANY character meal we've ever done!