I have stayed at CBR, CSR and POR and to be honest, they all have something to offer. I usually just pick whichever is less at the time I'm booking, which I know is not a very popular way of picking a resort. My thinking:
The buses are the buses are the buses. You are going to hear lots of opinions as to this resort has the bus best service and this one has the best. I've stayed at value, moderate and deluxe and have had good and bad bus service at all of them. I've waited 5 minutes and have waited a hour at all levels. There are too many factors involved so I take the buses out of the picture.
Theming - they all have their ups and downs. I love the mansion side of POR, it's quiet and peaceful and there are loads of spots to sit where it seems like there is no one else around. CBR, while undergoing major renovations right now, has it's own charms. Lots of beaches with hammocks to chill out but I'm not overly fond of the main building being so far from everywhere else but I've stayed in there twice and enjoyed it both trips. CSR has three distinct areas as far as the theming of the buildings. I've stayed in Casitas and Cabanas and enjoyed both. I love the fact that there are a number of places to eat other than a food court there. I'll be honest, I don't like the "feel" of POFQ, it just reminds me too much of a motel.
I really don't think you can go wrong with any of them.