I ask my kids questions like this all the time.
Attraction: Not just the best ride, but the best bang for your buck, somthing that lasts a while, if you get only one. At Disneyland, I'd choose Pirates, but it's too short in the Magic Kingdom. The very best attraction, The Tower of Terror, immersive as it is, seems too short, but what else compares? I'd go Haunted Mansion, but my guess is that the duration versus Tower of Terror is comparable. Nothing longer (Kilimanjaro Safaris, Spaceship Earth, Ellen's Energy Adventure) offers the same value... except The American Adventure. I find it inspirational and technologically amazing every time.
Show: Festival of the Lion King is the only show we never miss. It's getting a bit long in the tooth (sorry), but it's really Broadway quality.
Restaurant: Le Cellier, hands down. I can't believe that place still isn't a two-credit experience on the Dining Plan. Hopefully no one gets any ideas.
Snack: Norway's almond sweet pretzel. A close second goes to the frozen banana.
Parade: Whichever drains the crowds from the queues best; whichever prevents us from getting from here to there the least. But wait, I get only one of each, anyway, so who cares about the crowds? Something at night at the Magic Kingdom, but only if I have a comfortable spot on Main Street, U.S.A.
Fireworks: Ho-hum. Illuminations, I guess, because Wishes is harder to see and the throng in the park at the end of the day harder to navigate.