Both give you good food, but I think Ohana also gives you more of a "Disney vacation" experience. If I can only do 1, I pick Ohana.
Because you get apps and sides for the table at Ohana as well as the possibility of 4 different meats (you can have all, some, or just endless refills of 1 if you prefer), it's nearly as much diversity as a full menu like Kona. And if DD3 does not like anything there, Ohana will make her some of the childrens' classics like mac-n-cheese or a hot dog (I *think* they sort of borrow them from Kona since the two restaurants are essentially next door to each other).