Not a bad problem to be having - which great resort option to pick for a Disney trip. That said, just one curious question - your 6 year old mentioned Poly being her favorite resort - how many has she stayed at or visited? Has she ever stayed at AK Lodge or visited? What about various other
DVC options like Boulder Ridge or Boardwalk - has she visited those or stayed there? I ask only because you might find even more favorable
point charts that can fit in a 1-bedroom, and everyone might end up really loving that resort too - or even more. Boulder Ridge has boat access to MK which can be fun. Boardwalk has walking and boat access to Epcot and DHS.
If sticking to the two you mentioned, it's a tough choice for me as I'd always prefer more space and separation, so I'd tend to want a 1-bedroom. But I would prefer Poly's location and easier proximity to at least one park...I just don't know if I'd start to feel cramped with 4 in a studio - even a larger one that has two showers.