I think the best advice we received on the boards when buying our resale was to buy where you want to stay. We really like the boardwalk area, so we were on the market for either BWV or BCV. BCV resales don't come up as frequently I think because the resort is a bit smaller, so we ended up at BWV. We are really thrilled with it and really the best part is that we can stay at a top notch resort and save points by booking a standard view room - something you can't do at the other resorts. The standard view rooms are booked by the 7 month window, so it is not usually an option for non-BWV members (of course there are always exceptions but it isn't something you can count on).
To us, OKW and SSR are a bit out of the way and we like to be more where the action is, have dozens and dozens of dining options so close by, and walk to EPCOT and MGM. It all depends on what you like and want.
That being said, it seems you will find a huge group of followers of the boardwalk area on the boards, as well as a huge group of OKW and SSR followers (WVL is really kind of small, but they have their fans as well). You will often see the merits and negatives of each resort being debated often on the boards, and many persuasive arguments can be made for each resort, but I think it's something that you really have to have a feel for what you want on your own. What sounds good on paper might not be what you want in your heart. If you don't know which you are leaning towards, you might consider booking a stay at a place or two you are most interested in before you make your decision. Good luck!!!