I'm a newbie as I've only recently done a trip when my daughter was 4. But my now two kids will be similar in age (7 and 23 months). We are going with YC. My 7 year old will be floored by SAB, and we underestimated how much she loved pool days at Port Orleans. While it's not super duper themed, that's OK. I like that it gives that transition from park craziness. We wanted to have plenty of places to walk and wander to because our toddler is used to taking long walks, and often sleeps in her stroller. It's nice to feel like there's a boardwalk neighborhood to visit (and do stroller laps). YC/BC doesn't have a playground. We are going in the summer so it's not a dealbreaker for us. In February I might consider it.
What I would say I learned from our first trip is that what was important to my little one was sooo not what we expected. She really enjoyed being with the other kids doing activities in the pool, and would prefer to go on one or two rides multiple times. Literally she talked more about the pool than anything else. She didn't care for costumed characters, just the "face" ones. With this trip I'm letting everyone know they can pick one activty each, and if we only end up doing those 4 things each day that's fantastic.