WE prefer the PO. Actually FQ is our favorite but it won't be open when you are there, yet.
We have never stayed at Coronado but we did stop and look. We didn't like how spread out the resort was in regards to the room, pool, food court, main building. The pool was VERY nice, though. But, the slide seemed too much for our 3 year old.
As far as PO Riverside is concerned, we do like it. Our second favorite. We stay in the AB area instead of the mansions. To us them seem a little closer to the main building, food court, and first bus stop. That could be important with a 4 year old. We also like the "fishing" that Riverside offers. Of course, you have to pay a fee but since we don't do much fishing in AZ it is something my son likes. He also liked the pool area. The slide wasn't too big for him. Although he weighs such a little amount that he kept getting turned around backwards. The other thing we prefer about Riverside is the food court. At CSR you have to pay a 10% gratutity when you buy your food. You have real silverware and they deliver drinks to you, but that isn't important to us. At PORiverside the selection in the food court is very good. My son always found something he liked --mac/cheese, pizza, mashed potatoes, mickey pancakes, cereal, etc. Lots of fruit, cookies, bread choices. Good dinner selections, too. The boat, which I think is now running, to DTD is also a plus. You can either catch it or the bus. Two options instead of one is nice and with parks closing earlier in the evening during value season we spend more time at DTD than we do when we go in the summer.
As you can tell, our preference would be PORiverside. We like the AB buildings 14, 15, 16, and 18. There is a quiet pool right there and you are close to everything. I know there are some mansion buildings that are also pretty close but I don't know what they are.