I second the vote for POR based on it's themeing. Themeing, and immersing the guest in an environment, is what Disney resorts do best, and Riverside does the best at this job of all the moderates. The variety of buildings (manor houses and bayous), strolling the grounds, Old Man Island, the lighting at nightime, the Bridge and Mill.........you really feel like you are in the old south. In addition to being a wonderfully themed resort, POR (and POFQ) has a marina with boat service to DTD, POR horse and carriage rides, a nice food court and a decent restaurant. The kids love the pool. There is a lot to like.
Second favorite moderate would be CSR. It is the newest of the moderates, and being a convention facility it does have a few amenities that the other moderates don't have, like a lobby bar and a nice full service restaurant. Pepper Market is a different take on the food court concept, and one we like a lot. The pool and play area at CSR is very nice as well. CSR is very spread out, but the fountains and grounds are very beautiful. Nice resort, it just doesn't do as good a job at making me feel like I've been transported to the Southwest and POR does making me feel like I've arrived in the old South.
Renting from a DVC member is always an option, and a great way to stay at a resort like the WL, BC or BW for as little as $120 a night (on a week night), so long as you are willing to sacrifice a little of the flexibility (canceling, etc.) that you get when booking a reservation through Disney. We rented points to stay at VWL once, and now we own two DVC contracts. So be aware, renting from a DVC member can be a dangerous thing

.