Just got back from the YC, and I might be in the minority here, but I think SAB would be hard to keep track of young ones, it's so huge. I saw lots of parents trying to keep tabs on their little ones, keeping them out of the deeper end and saying that they couldn't go on the huge slide.
We have teens and they loved it, the deep lazy river, the large slide and the huge size of it all.
For a toddler, I would rather go for a pool that is more contained with a zero entry.
Volcano pool at the Poly is perfect for young ones. The Poly is a monorail hotel, so strollers on the monorail make an easy trip. Young ones love the theme, beach and huge rooms with bedrails on the daybed if you need them.
AKL's pool at Jambo house, we really liked AKL's pool and thought it was perfect for our younger kids at the time. There is a zero entry area and a nice playground. AKL animals, lobby and decor fascinate kids of all ages. AKL is more remote than other hotels, but we did not mind the bus ride (just plan for extra time). Our bus to MK from AKL took less time than the YC bus did, as we had multiple resort stops at YC before heading out to MK.