I voted for Ohana. It is my favorite meal at all of WDW. I love the Polynesian atmosphere and the setup of the restaurant. Try and get a seat by the window so you can see the Castle.
I really like the food and the way it is served. They bring you all you can eat right to your table. The meats are delicious.
Ohana's also offers kids activities during your meal. This would include Cocunut Races and Hula Dancing.
Now this being said I am biased because I love the Polynesian atmosphere. Others may prefer the African cuisine and choose Boma. It really depends on you.