We've done both
MNSSHP and the Pirate and Princess Party. We liked MNSSHP better (not that we didn't like PPP). IMO, the theming was better and the party more energetic and unique. The Boo To You Parade and Hallowishes (firework show) were just INCREDIBLE! While my kids love pirates and princesses, it is a theme that can be found somewhat through WDW daily. While we haven't done any other party, our favorite is MNSSHP so far!
You can't go wrong with any of them I think, really!