Wow, that is a tough choice. We went to both last trip and we had a blast. I think each one has it's own personality.
While WC is great for kids, loud bunch of waiters, always someone screaming for ketchup, or someone standing up to sing happy birthday to themselves, (if your kids are shy, don't worry, the waiters understand. our little cousin was too shy to ask for ketchup so she started eating her fries w/out ketchup and our sweet yet loud waitress quietly 'snuck' her one bottle of ketchup instead of the usualy 12). Over all, it was a really fun place to eat, IF you like the wackiness.
On the other hand, O'hana is a little more toned down. They do have activities for kids, like the coconut races and hula hoop contests. But there is no shouting waiters and there's a more calmer ambiance.
My vote is O'hana. We loved the food at both, but at O'hana it was more relaxed. We didn't feel that someone was going to make us stand up and sing or do something funny...we just enjoyed our dinner. (I don't know, maybe we're party poopers but we kinda though WC was a bit...too much).
Just my humble opinion, either way, they're both great experiences and I hope you enjoy!!!
