Since you are already doing 'Ohana, I would join the chorus and say The Wave. I personally would choose Kona over 'Ohana, but if I already had 'Ohana on my itinerary, I would have no burning desire to go to Kona as well. Not that the menus have a huge overlap, but there are enough similarities in style that I would want to try something else.
And if really young children are in the mix, I would bite the bullet and go to Chef Mickey's.