I will be staying at Port Orleans Riverside for the 4th time in just 5 more days!!
The only other resort I've stayed at was the Contemporary back in 2001.
Definitely

POR, it's a beautiful moderate resort. We always stay on the Mansions side. Have been in Oak once and Magnolia twice. We really don't care which Mansions building they put us in, because there are several bridges leading to the main pool area which is just another bridge walk over to the lobby and food court, etc.
They have a boat that goes to Downtown Disney (also bus, of course, but it's so nice and relaxing to ride the boat).
They have bicycle rentals, and horse and carriage rides.
And it's just a short walk over to the French Quarter too.
The landscaping and river are so pretty, and there is wildlife (rabbits and birds).
As a PP mentioned, there is a dedicated thread over on the resorts board for Port Orleans Riverside. You will find a TON of useful information there, plus there is a website just for POR as well (google it, I can't remember the name).