POR is our favorite moderate and we've stayed there many times. It's beautiful, fun, great for families. We like the Alligator Bayou section. There is nothing negative I can say about it.
We stayed at FW cabins once. We have no children, but were with another couple. The cabins were fun and nicer than I expected, but a couple of things to keep in mind. IMHO you have to have a rental car. The resort is so spread out that there are 2 internal buses that only run inside the resort. Then you have to take one of these to the main bus stop to go to the parks (or to the area within FW where the restaurant, store, petting zoo are). So it takes you 2 buses to get to a park. Also, the loops for cabins are kind of long, so you may have a long walk to the bus stop. It's really very beautiful and woodsy, but I don't think I'd stay there again although I know a lot of people love it.
I'm sure you'll have a wonderful time whichever you choose.