Check out the menu for each - though menus ARE seaonal - at all three places. Some itmes stay on the menu at each , but they also make changes.You can see the most up to date menus on Disney's own website. (look up each place and calling up menu is on the right side. Buffet menus are not available because they change daily, but the three places you list all have menus.)
The Wave is modern and has healthy options. It is perhaps not as highly themed as some other dining options on property. I only ate there for breakfast, but really enjoyed it. They have things like yogurt smoothies and a selection of herbal teas, and 'sustainable' fish.
Kona - more Asian in influence. In my mind, it went downhill after
DDP was introduced. Last trip we treid the sushi bar though. It was S-L-O-W, but tasty. I may try Kona again at some point. My newer love is 'Ohana next door though! In the past, Kona was known for a big selection of
really cool desserts. I don't really know what they have now, at last visit I was a bit disappointed in the reduced offerings.
GF Cafe - I liked it, but it also is not particularly high themed. The portions were plenty to share. I had the pasta on last visit. They also had a great chocolate dessert.