I've stayed in both, but we had a car which makes it easier in those big, sprawling resorts. OKW has my heart after many stays over Christmas period, but the food options are limited compared to SSR. The proximity to DS is a definite plus for SSR but as we go in December I didn't feel comfortable taking the path to DS in the dark (maybe that's just us), and feel more comfortable on the boat from OKW.
The choice of building in each resort (if you don't have a car) can be a deal breaker also. At SSR if you're near DS you are quite a way from the resort's main building/dining options so there is a trade-off. Also, we are 'early to bed early to rise' people so were worried at SSR about noise from DS late at night.
Overall OKW wins out for us, but it's not always possible to put your finger on why your heart chooses one resort over another.