I love both resorts, but I would personally not base where I stay on where I want to eat. I usually eat meals and/or enjoy the lounges at both resorts, and I really enjoy the walk from one to the other, especially after dinner. As for rooms, I find the GF quieter, which is a plus, but while I adore the GF 1-bedroom and larger units, I don't really like the GF studios all that much. Studio vs studio, I prefer the Poly decor, space, and storage space.
That said, given you're talking about August 2015, I might prefer GF studios, simply due to ongoing construction and growing pains at the Poly, especially if you've booked a standard view (which at Poly could be parking lot or, by August, potentially looking over the quiet pool construction from Tokelau). So if Lake view, I'd stick with Poly, but for this August, I'd try for GF.