We ate at both restaurants last week: Kona on our first night and Ohana on our last. I would say that, overall, I preferred the food at Kona (my husband had the Pan-Asian noodles and I had the ginger-glazed rib eye -- both were yummy!). Our server at Kona (ask for Marisol!) was friendly, efficient, and good with our children, and we didn't feel rushed at all. Of course, the atmosphere at Kona IS more like a coffee shop, as a previous poster noted. IMO, the desserts at Kona were far superior to Ohana's, but then again I'm not a lover of bananas or caramel.
Our children preferred Ohana because of the children's activities (dancing, limbo). My husband loved the quantity of food and thought that everything was great except the turkey (too dry). I preferred the nonmeat items because, again, as previous posters noted, the meat tended to be a bit overcooked and dry at times (and we're a family who orders steak cooked medium to medium well!). I thought the pork was the tastiest meat. We polished off all the starter items though! The sauces were great too.
I'm extremely glad that we ate at both restaurants, but I'd say that if you have children, Ohana is probably the better family experience. On the basis of the food alone, I'd probably pick Kona. You can't go wrong with either choice, and you can always try your second choice on your next trip.
Enjoy!