If it has to be only one thing, then my first thought is BOG lunch.
Runner-up is Trail's End dinner.
I read through everyone's responses, and I agree with those who posted these that the following are also overrated:
Rivers of Light (underwhelming)
Wishes (it was fine the first time; didn't need it repeated for so many years)
Fantasmic (ditto)
the dining plan
Chef Mickey's
CRT
V & A's
Le Cellier (not bad, but I feel that it is overpriced for what it is)
Ohana (food and service are hit or miss)
7DMT
dessert parties
Frozen Ever After (Maelstrom was more interesting for me)
pin trading (why)
Disney Springs (IMHO it is much too overgrown; it's like the kudzu of shopping complexes)
Poly
It reminds me of the Brady Bunch goes to Hawaii episode.
Great episode! I'd see that association as a positive.
now I'll do a public service of my own and give a response to each, showing why each is awesome....IN HAIKU FORM!
Jungle Cruise
Lasseter would say
You've got to embrace the kitsch!
Backside of water!
I really liked all your haikus, regardless of whether I like the various things they refer to. I'm a Jungle Cruise fan, and your Jungle Cruise haiku is one of my favorites.
Chef Mickey's
You get to eat and
Meet Mickey while monorail
Whizzes overhead
That's better than meeting the monorail while Mickey whizzes overhead!