You are correct in your summary of the benefits of these resorts - OKW gives you more living space, while SSR has better pools. We have stayed at both resorts and couldn't agree more.
The 2nd bedroom at OKW has two queen beds, which is nice if that means something to you. (The 2nd bedroom at SSR will have one queen bed and one sofa bed.) OKW also has a very nice sized balcony, with a table that seats four. SSR's balcony is much smaller, with barely enough space for a cafe table for two. OKW's main pool is very enjoyable - especially for kids your age. A sandy play area and the sandcastle waterslide, but no zero entry area at any of their pools, if I recall. Other than the main pool, I do not believe any of their other pools have any fun offerings.
SSR, on the other hand, has three pools that appeal to kids. We have enjoyed them all over the years! Lol! The new Paddock pool might appeal to you the most, as they have a water play area that is ideal for your 3 year old. Two of their four pools have a zero entry area. Will you have a stroller with you? If so, you may prefer SSR as all their buildings have elevators. You can also walk to DTD from SSR, although that doesn't appeal to everyone. You can take a boat there from SSR or OKW.
The bottom line is that you will have an amazing vacation wherever you stay! You just need to decide what your priorities are. If you have other questions about the comparisons between resorts, I'd be happy to share any of our experiences with you.