If you will be at MK other days and have chances to go on the attractions, then I would prioritize maybe just attractions with overlays. Then meet some characters in costumes, take the magic shots, get candy, eat special party food (pay for) and watch the parade!
We haven't been to a true Halloween party since 2017 (did the Boo Bash 2021, during the covid years) and last year we went to the Christmas party for the first time. While that was fun, it had nothing on the Halloween Party. Just the atmosphere is fantastic!!!
We are so excited to finally go again!
I hope you guys have a great time.