I have stayed at both with family and both were extremely nice. You will enjoy both and I wouldn't hesitate to stay at either.
With that in mind, I think that SSR has it way over OKW on quick-service dining. As for table service, I thought the food a Olivia's was great, but likewise enjoyed Turf Club even with its more limited menu.
The pool at SSR was probably a "smidge" nicer and SSR has better access to Downtown Disney, although the boat ride from OKW to Downtown Disney wasn't bad either - it just took longer.
As for the villas, OKW has the larger rooms, which was nice, and the feel of the resort is more "vacation-like" with the tropical feel. However, SSR had a tranquil feel to it that I enjoyed.
In other words, it's a tough choice, but you'll be happy with either outcome, I think.