All depends, IMO, on how often you are going to go. When I first bought in 2009, I bought BLT because I knew that is where I wanted to stay on my yearly trips, wanted SV to maximize points, and didn't want the hassle of dealing with a 7 month window. Fast forward to 2019 and I know own BWV and SSR. I added on BWV because I started going yearly to F & W and wanted 11 month advantage for that. Two years ago, I sold off the BLT to purchase more points at SSR because I am retiring and knew I would be going monthly and knew, because my travel times would be flexible, that I would surely be able to stay elsewhere at 7 months if I wanted, especially since I am no longer locked into school vacations.
As you mention, 1 bedrooms tend to be the last to book up so that will work in your favor. If you are okay staying at SSR if you can't get into BLT, the go for more points. If you see yourself traveling during the busy DVC times...October through after January 1st, especially December, you won't have a lot of luck trading into BLT at the 7 month mark, even for 1 bedrooms as most book 11 months out for travel during that time.