POR gets my vote.
We've stayed at all of the moderates, except POFQ. So I can't speak to that resort, nor can I speak to convenience if you're talking about bus service because we either drive or rent a car when we fly.
POR feels the most deluxe of the moderates in my opinion. The grounds are absolutely beautiful and I love the two distinct sections. What other moderate offers horse and carriage rides through the grounds and a boat to Downtown Disney? In our experience, the CM's are top notch at this resort, and we usually stay deluxe. They absolutely stack-up! I remember one time we were leaving our room for the morning and a CM said "Good morning, thank you for staying at Riverside. Have a magical day!" I was blown away by that.
They have a nice sit-down restaurant, Boatwrights and in the evenings in the River Roost Lounge they have Piano Bob. He is tons of fun! I don't think the other moderates have entertainment.
The rooms have always been clean and fresh - never a problem. We've stayed there 3x.
CSR used to be our favorite moderate, but during a recent trip there I was very disappointed. I don't think they are keeping that resort up as well. The room was dirty and messy, the heat (It was a cold late November trip) broke and it took 2 days for them to do anything about it. POR feels more "Disney" and "magical" to me.
Haven't stayed at CBR in a long time, back in the 90's, probably 1998 was the last time. We loved it then. But nothing beats POR in my book. As far as a moderate anyway. If for whatever reason we can't afford deluxe on a given trip, we will always choose POR.
PamNC