We ate lunch at Kona and dinner at Ohana. We left MK at 1:00 for lunch at Kona. It was a nice quiet break from the park, the food was delicious (I had the pan asian pasta, hubby had a sandwich), but the desserts were the BEST - the kileau torte was to die for, and the kiddie cone was so fun. We would eat here again but wouldn't go out of our way for it.
Ohana was one of our favorite meals. We loved the shrimp, potatoes, salad, some of the meats, and especially the bananas foster. My youngest loved the singing and dancing and coconut races. It was really fun. We'll definitely return to Ohana.
So in my opinion, try both if you can, they were both good. But if you have to choose one, stick with Ohana.