We are in a minority of folks who dislike the food at Ohana. Its a beautiful restaurant, and a fun place if you have kids who want to participate in the activities, but we've been several times, and think the food is mediocre at best.
Kona Cafe, on the other hand, is one of our favorite restaurants. It's kind of just the opposite of Ohana--its a rather plain, unthemed place, but has incredible food and service.
If you have young children who like to play, Ohana is a good choice, but if you are judging on food alone, Kona by a longshot!