I'm sure we could start a regular Poly vs. GF debate, but I prefer the Poly. The GF is beautiful, don't get me wrong - we had a wonderful stay there. But it's the Polynesian we keep going back to, and these are my reasons.
1) Theme - Although the GF is pretty, we just don't feel a real Disney theme like we do at the Polynesian. With the tiki torches, the piped in music, the friendly cast members Aloha-ing you whevever you go, you feel like you're in that Disney magic 24 hours a day.
2) Location - being within walking distance of the Transportation and Ticket Center is a huge advantage. We request the nearest builing to it and with it's path to the Epcot monorail, you really chop off some travel time and bother.
3) Pool - We just like the one at the Poly better. With its "erupting" volcano, again, more magic.
4) The rooms are huge. The rooms are more modern looking at the GF, but I would bet that the rooms at the Poly are some of the biggest at Disney.
and finally...
5) It's cheaper than the GF - at least that's been the case for me. I supposed that people have, on occasion, found a great rate at the GF, but on the whole, we find a better rate at the Poly. For instance, we just planned a relatively last minute trip and the Poly was the only resort I could get a Disney Club rate at. So, with reasons 1-4, we don't see a reason to pay more.