How many people? If it's more than 2 people, I would never choose a DVC studio (except OKW) because once you pull out the sofa bed for sleeping, you give up all of the room space.
If it's just two people or a third that is small enough to sleep on the sofa without pulling it out, I would then take SSR. Reasons: the resort is very nice; 2 themed pools, a very good CS and TS restaurant. Ability to walk to DTD. As far as the room itself, SSR rooms will have a private balcony or patio (very hard to access it if the sofa bed is pulled out tho). There is also a kitchenette with a small refridgerator, microwave, toaster. The bathroom setup is nicer also.
One of the downsides to the DVC studios is the lack of storage space. You will have the closet and 2 drawers under the TV. That's it. Not much drawer space at all.