You will get so many different opinions on this.
I prefer eating in MK for a nice sit down meann with my ADR no later than 5:30p; that gets us out of the restaurant by 6:30p -6:45p.
I've eaten at Chef Mickey's, the Castle, LTT, CP, and Tony's before parties.
I enjoyed CP and Tony's the most for the food and the atmosphere. We didn't enjoy the food at LTT and the Castle is just too expensive now.
Some people prefer eating outside the park and then heading to the party.
Some people prefer eating a CS meal instead of a sit down meal.
Some people prefer eating really early, around 4:00p, rather than later.
I do suggest though that you do NOT eating during the party as there are so many fun things to do that you paid extra for.
You'll have to decide what's best for your family and your schedule.
Have fun planning!