Poly with the slight lead in the poll
Yacht Club rooms are 380 square feet. Poly DVC rooms 447sf.
Poly 2 showers. YC one.
Poly has more pool and hot tub choices. YC’s Stormalong Bay is like a mini water park but I’d take a look at a walk through video and consider how it might work with your family. Then look at Poly options. Compare the room as well.
I love the location of Epcot area resorts. YC is pleasant 7 minute walk into Epcot. Walking to hollywood studios is closer to 20 minutes and the only other option is boat. The boat is lovely but hard to beat Poly where you can monorail to both MK and EP, take the ferry or resort boat (recommend this one at least once).
Between these 2? Try Poly this time and save BC/YC for when the average age of kids is older and the pool will be more fun for the
whole family
. If you do pick YC - try the Ale & Compass breakfast. A hidden gem!