I would personally stay at the Poly. Although I've never stayed at the AK, I would prefer the convenience of the Poly, particularly its proximity to the MK. When we went with my 1 yo DS, we spent a majority of our time at the MK, and the convenience was awesome. My son would fall asleep in his stroller at the MK, and we'd be able to get back to our room with him still sleeping (strollers don't need to be collapsed for monorail - only for busses). Also, you're so close to the GF, which I'm sure is every little girl's dream - you could easily walk there from the Poly. The Poly is my favorite - we're staying at the GF in December with my now 2.5 yo DS, and 8 month old DS simply because we're going with my mom and she wants to stay there. Otherwise, we'd be back at the Poly.
Also, not sure if you're doing garden or lagoon, but we did lagoon view, and it was wonderful - the beach was right outside our door - your daughter would probably have a ball playing in the sand. Oh, and there's the Electrical Water Pageant every night that you can see from the beaches of the Poly - something really cute!
Have fun!