The common sentiment here is buy where you want to stay and I think thats good advice. Besides location and the theme of the resort, the big difference is SSR expires (reverts back to Disney) in 2054, while the other current resorts expire in 2042, so youll get an extra 12 years at SSR. You can also finance SSR through Disney, if you buy resale youll have to line up financing on your own and the process takes longer to complete.
We recently went through the same decision process and decided on a BWV resale. Ill be 78 when the BWV contract expires, so I wasnt concerned with the extra 12 years at SSR. (Not to imply that people in their 80s cannot enjoy WDW) We love the location of BWV because its close to Epcot and the restaurants on the Boardwalk. Itll be about six weeks from when our offer was accepted until we got into the system to make reservations. It was a long wait but well worth it.
Good luck with your decision!