I agree with Claire as far as December being a better time to go. Christmas extends all over the resort with decorations and other shows while Halloween is mostly only during the party hours. There were some pumpkins in the Main St. windows and autumn/pumpkin displays here and there. We were just there a week ago and it was much more crowded than Labor Day was even.
It also depends on what you enjoy more. I love Christmas at Disney for the warm fuzzy feeling but Halloween was truly a PARTY...with awesome music and dancing and fun.