If you want to own at BW then it's likely you'll find a resale is your best route. If Disney does have any points for BW come up I think they tend to go as "add ons" to existing members.
Saratoga Springs, which is what Disney is now selling does have the advantage that it is for a full 50 years length of use ( as opposed to 40 for the other resorts) , but if you are a more mature purchaser that may not be so much of a bonus as it would be if you're in your 20s. Obviously there is a large (potential) financial advantage to having the extra 10 years on the life of the points but that may be countered if the price of a resale is significantly lower than buying through Disney. There are some good deals about for resales, particularly if you can find one with banked points.
The main advantage of a resale is it's a much smaller initial outlay, the main advantage of SSR is it's an extra 10 years of life.
Use year isn't a huge factor, but it does make your life a good deal easier if you have some time between when you usually vacation and the end of your year. The potential problem is if you have to cancel a vacation at the last minute and your points go into a holding account. They need to be used by the end of your use year. If your use year ends a matter of weeks after your vacation it could be very difficult to be able to use ( or rent ) the points. If you have 5 or 6 months then it gives you a lot chance to reschedule.