No hoppers- got it. So do you already have an extra park ticket purchased for the day? Where are you staying? ADR at 430 means you probably won't get to the party till 7. Eh. For the money you spent on the party I would absolutely want to get my money's worth and get there by 4. Plus- I'd be more relaxed knowing I didn't have to go from one park to the next with a five year old.
My first choice- BBB if and only if you were already planning on using another park ticket to get in early.
Second choice- neither. Relax at the resort. Sleep in. Explore. Head to MK at 4pm for the party