We were wondering the same thing a few months ago and we chose Saratoga Springs. We made our choice based on the fact that we are just a couple and from what I've read, SSR is the more adult of the 2 resorts. Rooms are somewhat smaller, but newer. The studios at SSR have a double bed and a sofa, whereas OKW has 2 double beds but no sofa.
Plenty of photos can be found on the resort section of this website and on Allears.net
Another vote for Saratoga - because for us it was great for kids
We went last month and stayed at the Grandstand area with ds3 and dd12. We just got off the Disney Cruise so wanted a few days in a nice resort (with no parks) before going home. It was a real hit with us all, beautiful resort, comfortable rooms, we loved the sofa bed because it gave us extra floor space during the day. The pool area was a big hit, fab splash/play area for ds and bigger pool for dd. We could refill our mugs at the pool bar so no need to walk far for drinks.
Excellent boat to DTD and not too far to walk either. Gorgeous grounds although dh almost cried to see the golf course knowing that he didn't have time to play on this trip
I think that was a real plus when SSR was built and DTD was a great night-time destination - but now it is largely MORE shopping/dining opportunities, I think it's devalued. However, you can still have a pleasant boat ride to DTD from both OKW and SSR if you choose - oh, and you can also walk there from OKW; it's just further!
I'm biased in favour of OKW because: if I'm there with my friend then I want 2 proper beds in a studio (and OKW has the largest of all the DVC studios) and if I'm with DH, then I want a 1 bedroom which are huge and have great balconies. Additionally, parking right outside the villas is the most convenient at OKW. Oh, and I just love its tranquil setting - because it was the first DVC resort to be built and they used up so much land (never the be repeated) and landscaped so lushly it can feel almost empty even when full.
I do think that SSR is a very attractive resort though and the dining options are better there. Depends on what is important to you.