For me it's simple: It's the dark rides, the audio-animatronics, and the coasters. I've always loved all that stuff.
Don't know if anyone knows this place, but I grew up going to Rye Playland in Rye, NY. It's the park used in the beginning of the Tom Hanks movie "Big." They have a dark ride where you ride in a boat, called "Ye Old Mill" that I always loved (rides when you're in a boat are my favorite). Also a couple of crappy, scary, carnival-type dark rides. Their big coaster, the Dragon Coaster, was my first one and I still remember the first time I rode it with my dad (my older and younger brother were too scared
). Then I graduated to The Cyclone at Coney Island. And Coney Island has (had?) a couple of crappy dark rides too.
WDW has a large collection of these things, and they combine them all very well. And while they refurbish the rides, the older and more rickety the dark rides and audio-animatronics get, the better the experience IMO.
Also, we don't go to any of these places very often, so it always is a nostalgic, new-again feeling on any of the rides.