Lights, Motor, Action! Was one of the best WDW attractions of all time. I'm looking forward to the future of Hollywood Studios; however I wish this attraction could have some how been salvaged. All the new attractions, plus this show would help boost Hollywood Studios into the upper theme park echelon.
Alien Encounter was a great attraction as a kid.
I also miss Body Wars & Test Track 1.0. (Radiator Springs Racers is 10x better of an attraction than either Test Track version imo)
It was glorious; an overwhelming sensory experience in the best possible way. My family went to EPCOT Center in the summer of '83 and, though the lines were the stuff of nightmares, the attraction was worth every hour of wait time. Sadly, I only got to experience it one other time, in January of 1997. Had I known it would be the last time, I would have taken the time to ride it several more times and really savor it. Regrets, I've had a few.
Closed/Forgotton - ...basically all of EPCOT, Horizons, Original Journey Into Imagination, World of Motion, Dream Flight, Original Test Track, Mr. Toad, Snow White
Closed: Snow White's Scary Adventures, Maelstrom, Studio Tour
Forgotten: Peoplemover, Dinosaur, Country Bear Jamboree, Wonders of Life
Underrated: Journey into Imagination, Maharajah Jungle Trek, Tiki Room
Enchanted Tiki Room and the PeopleMover are definitely my two favourite under appreciated attractions.
My favourite attraction that is the Discovery River Boats in Animal Kingdom. They were around for such a short time nobody remembers them anymore.
My favourite attraction that has since been closed is actually just the Wonders of Life pavilion. It's a fairly simple one considering how the pavilion is still standing there intact but very time I go to WDW I'll probably spend 10 minutes just staring at that old thing wanting to go inside!
I miss Light, Motors, Action but I really really miss Studio Back lot tour/Catastrophe Canyon. I always though it was so cool seeing behind the scenes and getting close to some really cool props. In my opinion it was the attraction that tied so well with the name of the park. I also miss Maelstrom. As for most underappreciated for me it is Living with the Land.