We have stayed at both. Riverside is larger. It has a main, themed pool and quiet ones (no theme). The food court is good and Boatwright's is the sit down. We really like it, and eat there once a trip. The resort has the bayou and mansion sections. There are four bus stops around the resort. It is much bigger the FQ
We prefer POFQ, since it is smaller. We have little ones (now 3 & 6) and all of the rooms are close to the main sections. My Dh and I like the theme of the resort better, also. It doesn't have a sit down, but it's a short walk to Riverside.
The bus picks up and drops off at FQ first. That's another plus.
We stayed there last December, again and loved it. I also think I have a soft spot for FQ since it was the first place I satyed on site, way back when!