Do you have to take cost or points into consideration? How long are you staying? If it's a week than I would choose by the resort I like best. Check out the pools since that's what kids really love! It is hard to choose. I love VGF, but they are expensive or you may not have enough points. I love OKW because the living room is very spacious for a kid to move round in. SSR has some really fun pools. AKV have the animals. Having a car can make a difference too.
I would not choose the resort based on the child. There are thousands of families that don't even stay on the grounds and have a great experience. A bus ride can be a hassle or not. The walk to BLT isn't short for a tired child, and we personally don't care for the theming of the resort.
Lots of variables to consider. It can be fun to plan though.
Our first trip down with grandchildren will be to OKW since our points will get us a larger unit to spread out in, and the car will be close to the door.