'Ohana will depend on if you want to see characters. I can't stand Lilo and Stitch so I'd never eat there for breakfast but other people love them. If those are favorite characters for your family, go for dinner. It's tasty and fun, but no characters (they do have some interactive activities, like hula hoop contests and pineapple races)
I think Kona is better at dinner, their breakfast stuff is pretty basic breakfast food with the exception of 2-3 entrees. Their dinner was really good, we thought. Look at the menu at both and see which appeals to you the most.