I would do both!
They are completely different atmospheres & food so its tough to compare.
Ohana - very busy hawaiian atmosphere, entertainment for the kids, possible Wishes view, somewhat limited menu (the same for everyone), lots of yummy grilled meats, bread pudding dessert
Cape May - semi-busy beachy atmosphere, no entertainment, no views, lots of seafood & big buffet food selection, yummy crab legs, not so good dessert other than the oreo bonbons
Both are really good & worth doing if you can do both. But if I had to choose, I would do it based on the menu & atmosphere.