I’ve done both and I prefer SSR. That being said, I truly enjoy the amenities of the resort rather than the room itself. SSR offers a lot of great “morning walk” opportunities along the golf course. It’s walkable proximity to Disney Springs is great if that something you enjoy. Lastly, while SSR doesn’t have a lobby per se, it does have Artist’s Palatte with quite a few QS dining options for breakfast, lunch and dinner. I do agree with the others, the theming isn’t great at SSR. Another benefit with SSR, which another poster mentioned, is that the buildings do have elevators, which is great for luggage and those with mobility issues. I also feel the pools at SSR have better theming.
My issue with OKW are the few options for QS dining if you return to your resort during the day. However, the larger size studios are nice. As the previous poster noted, you are going to have an internal bus system at either resort. If you have a car, there is ample parking at each resort just a short distance from your room, which is nice.
Either are great, hope you have a nice trip!