I don't think there is a "best" moderate. They're all nice and each one is somebody's favorite. It's just a matter of deciding which one will best suit your tastes.
Personally, I like POR the best. The landscaping is very lush and private. The theming is very fun in the Alligator Bayou section and romantic and elegant in the Mansions section. The pools are very nice, both the main pool and the adult pools. Plus, it's fun to be able to ride the boat to Downtown Disney.