we've never been to the swan/dolphin, so can't comment there.
however, both my kids, as well as my nephews,
greatly prefer luna park over SAB. on seperate visits to the BC & SAB, they all asked to go back to the BW.
as PP said, SAB has quite a few "fun" parts. despite its size though, it has always been very crowded when we've gone ~ many guests go to the BC specifically for the pool. ("crowded" as in difficult to swim b/c you are literally touching other ppl, no chairs unless you are there upon opening, and
extremelly loud).
SAB is definately worth a visit (especially during the colder months when it might be less crowded) ~ it is very pretty with interesting features that i don't think can truly be appreciated with too many people.
btw, we've gone to BW at the same time of year, & have had no problems finding chairs/tables, the kids were able to repeatedly use the "scary clown"

slide (which they love), & actually swim about the pool freely

.
btw, both resorts also have beautiful "quiet" pools without a slide, but imho, very enjoyable if you want some quiet time & swimming.
hth
