I've only been to Kona but given the choice I'd try the GFC instead.
While the Polynesian had great atmosphere, I actually found the restaurant to have little atmosphere at all. (There's a guitar player?) It just seems like a big open space set up almost cafeteria style. The food was okay. If we had to, we would probably go back but not with all the other options at WDW. We really enjoyed our drinks. I hear it has a really great breakfast, so maybe it depends which meal you go for.
Just wanted to throw in my two cents...