The Poly for sure!!! The rooms are huge, plenty of room for 5, as one can sleep in the day bed. The Poly rooms all have daybeds, that are very comfy. My DD and DS fought to sleep on it at night.
The Poly has the best transportation, super easy walk to the TTC to catch the EPCOT monorail or a bus. Monorail or boat to MK, takes 5-6 min. We thought the buses to the other locations were very quick, and buses came often.
The Poly volcano pool can be crowded, but we like the quiet pool too. Watching Wishes from the beach or pool is wonderful, much better than fighting the crowds at MK.
My vote is for the Poly