I would say The Yacht Club, or if you dont mind a more family/child friendly atmosphere, then the Beach Club. I prefer the Yacht Club. I use a wheelchair alot but transfer and walk sometimes too. The
ECV can eaisly load onto the friendship boat for transportation to DHS and Epcot and you can even just ride in the
ECV on the path right into the International Gateway (back entrance) to Epcot.
The bus transportation is good, but we did notice the lack of Magic Kingdom busses, for like every 3-4 busses, the 5th one would be a MK bus. It would be like 2 to AK, 2 to DTD etc. then the 5th one was MK.
Hope your friend has a great trip.