Remember most of the ohana meal is meat! So if you love meat it is the meal for you. Our fav. part is actually the side dishes you start with but the meal is based on meat. Go early to allow digestion, and go hungery!
Quality-wise, Kona is the better restaurant - great choices, excellent food. It's one of our favorites overall. 'Ohana is more the "fun" restaurant - a lot of food, but not as tasty, but you do get the entertainment.
It all depends on what you're in the mood for - better food or entertainment.
If you have children with you, Ohana is the better choice - my dds had a great time this past october - they had hula lessons, coconut races, ect... Not to mention the food was very good, and if you time it right, you can see wishes at the MK.
We hated Ohana's. No silverware and we were told "oh, we ran out". Try eating salad without a fork! They finally dug up some plasticware, but we were kind of ignored by our waiter. Beef was tough, and the meal was mostly meat. We were a large party on the food plan.
We absolutely love 'Ohana's. Our last trip there in December we had a wonderful meal (again) and a fantastic waiter (very attentive and helpful). We highly recommend it.
Kona Cafe was one of the bst meals I have ever had at WDW, I cant wait to go back. My DS had the steak terriyaki and he is still raving about it. I had the mahi mahi and will probably get that again as it was so good! Ohana's is too much meat for me.