I faced this exact same decision this past July. You can tell from my signature what choice I made. Although that choice was definitely the right one for me, I wouldn't recommend it for everyone.
If you like VWL but would be perfectly happy to stay at SSR if VWL was unavailable, then you'd be a lot better off buying at SSR. You should also buy at SSR if you know you won't be able to plan your trips more than seven months in advance. You get 12 more years at SSR, and depending on when you buy, there's usually some sort of promotion in effect. (The current promotion gets you park tickets.)
The advantage to buying at VWL is, of course, that you can book at VWL 11 months out. Even though I own at VWL, I don't want or need to stay there every time. The reason I went with VWL is that I know myself, and I know that if I bought at SSR and decided for a particular trip that I wanted to switch to VWL when the seven-month window opened, I'd take it in stride if I wasn't able to do so the first time I tried. However, if I was unable to switch after trying two or three times, I'd become very angry, bitter, and stressed. I don't need to stay at VWL every time, but I knew I definitely wanted to stay there sometimes. Buying at VWL took away all that stress for me. If I want to stay somewhere else but am unable to switch when the seven-month window opens, I can take it in stride because I'll still be able to stay at the place I like best.
So it really depends on your tastes, preferences, and temperament. If you do decide to go with VWL, my experience was that despite my guide's initial claims that VWL was sold out, points at VWL were readily available. I didn't have to wait even a minute for my initial contract or my two add-ons. (I bought directly from Disney, though I've heard nothing but good things about all the leading resellers, including the board sponsor.)
Good luck whatever you decide.