We have stayed at both. I think it depends on what you want. Both have different strengths.
The POFQ is smaller than Riverside (1000 rooms vs. over 2000). It is much "quicker" to navigate the resort. If anyone in your party has a difficult time walking distances then the POFQ might be the best option. I also think it is better for younger kids. It hs large courtyards of grass that kids can play on, if they want to do that. Most are located directly outside one of the buildings. The playground is also much better suited to younger kids (5 and under) as the one at Riverside is more rustic and more challenging in regards to climbing, dirt, etc. POFQ is on mat type material where Riverside is on dirt. The pool at POFQ is also very appealing to younger kids. The slide is not as long and windy and the theming for it is very nice. They only have one pool, though, while Riverside has the main pool plus quiet pools, too. As far as the food court, we typically like the one at Riverside better. However, the one at the POFQ has been refurbished so I'm not sure if that will be the same.
Also, in regards to transportation. POFQ is the first stop for you to get on and the the first stop for you to get off. If it is busy sometimes the buses go directly to the parks without going to PORiverside. If not, the bus will stop at FQ first and then make the rounds at Riverside. Riverside has four different bus stops. We prefer FQ since we have a young one and it is very nice to be the first off at night.
Riverside has a sit-down restaurant and FQ does not. So, if you prefer that then Riverside is probably best. Also, Riverside has a fishing hole that the kids can use for a price. If you stay at FQ then you can walk over and use it too. Finally, all the bikes, boats, etc. rentals are at Riverside. You use them at both resorts but you must pick up and drop off at Riverside.
We prefer FQ better because of its size. Seems a little more intimate and not at big. If you like remote and don't mind the walk then Riverside is also good. There are a few buildings that are centrally located but there is no guarantee you will be in them. At FQ most buildings are pretty centrally located since it is smaller.
You will like either resort. They are both great.