It's a truly terrible question...but I understand it.
This reminds me of Epcot, and how they took incredible E ticket attractions and replaced them with stuff that never quite lived up to the wow and wonder of what came before.
That said, I would vote for the castle.
Unlike the other three...it's not a ride, with amazing effects, and awesome music, and incredible innovation and themeing.
It's a weenie.
It's a nice weenie, to be sure...but it's still just a big photo background with overpriced food, when it comes down to things I would grieve over.
The experiences and memories of the other attractions far out weigh my experiences with the castle.