We just dined at both. Whispering Canyon Cafe is very different from Ohanas.
At WCC, it is loud and rambuncious with lots of entertainment from the servers. They get the kids involved when someone asks for ketchup. They had men dancing up at the front of the restaurant. DS2 enjoyed being able to build Lincoln Logs when he was finished with dinner. Ohana's is darker and quieter. They do have hula hoop contests and coconut races which the kids enjoyed.
Food wise, we prefer Ohana's hands down. Most of their selection is meat. Turkey, steak, pork. They have shrimp too. They had some chicken wings that were to really excellent. Our DS8 who is a picky eater could not get enough.
At Whispering Canyon, the food was good too. They had chicken, ribs (which we thought were tough). The best was the pulled pork. Our DS8 ended up ordering mac and cheese because he didn't like any of the other selections.
I don't think anyone could be disappointed with either because they are very different from each other. For our family though Ohana's will be in our plans next trip, WCC will not.
Enjoy whatever you decide!!