Two distinct choices. O'Hana's is very family friendly (games for kids) and is an all-you can eat. The food is brought to your table - not buffet - and is a set menu.
Kona is more like a regular restaurant where you are seated and then given a menu to order from.
I personally prefer O'Hana, but I'd make the choice based on "set menu, all you can eat" or "order from menu."