We have been to both
It was fun to watch everyone in their costumes for the Halloween party and also it was fun to trick or treat as an adult and the fireworks were very good. We didnt do the character lines.
Personally I prefer the Christmas party. The cookies are terrible and the hot chocolate is ok if it is a really cold night. I enjoy the parade and the shows. Puts you in the christmas spirit mood. The snow on Main Street is fun too.