I own at OKW and love it. We've stayed at every DVC resort (and like them all) but OKW is still our favorite, because it has a very relaxing atmosphere that offers a nice escape from the parks. Someone else said the rooms are more "homey" and I agree. The buildings are more like homes too - smaller, no elevators, no real hallways. At OKW, you walk up the stairs to your room - the only people who might be walking outside your room is the maid and maybe the people living above or right next to you.
In contrast, SSR (and pretty much all the more recent DVC villas) feel more like a hotel. You take an elevator to your floor and then walk the halls to your room. Our room was near the elevator, so we heard a lot of noise outside our room - constantly reminding us that we were in a hotel, not our "home away from home".
That said, I really enjoyed SSR. It's also fairly quiet, and the main pool is really nice and relaxing. I liked being able to walk to DTD, but it is quite a walk (longer if your building is far away, which ours was). The snack bar at SSR is nice because it offers some interesting options... I didn't like that it was pretty far away from the pool, though (I still prefer the burgers & fries snack bar at OKW). We ate at the Turf Club and really enjoyed it (although I still prefer Oliva's at OKW).
SSR is quite a bit newer than OKW... I've never had a bad experience at OKW but the resort shows it's age if you happen to get a unit that hasn't been rehabbed in a while (I think they are working their way through the resort rehabbing units.)
I usually rent a car for OKW because the bus service isn't always the greatest (can be waits of 20-20 minutes if you just missed the bus). We rented a car at SSR also, and didn't even try the buses. I was nervous that the buses would have to leave SSR and then go to the Treehouse Villas, taking even longer. I'm not 100% certain that's true, though - maybe someone can advise.
For me it comes down to this: If you want to feel like you're staying in a "home" where you can relax away from the crowds at Disney, choose OKW. If you want to feel like you're staying at a fresh, new hotel, but with all the benefits of DVC, choose SSR.
Good luck - you really can't go wrong either way!