I've visited every resort and have stayed at over half of them, but none are as good as Animal Kingdom Lodge for me. It is a resort that you are under shade/cover from the time you leave your room, walk out the lobby, and to the bus stop and vice versa. Going in the summer, this can be a huge advantage when dealing with heat, rain, and thunder storms.
I love the lobby and having that as your welcome back to the resort every time you get back from the parks. I think The Mara is the best of the deluxe resort food courts and rarely has a huge crowd. The room layout is also perfect to me, especially the restroom layout. At the Polynesian the sinks and and shower/toilet area are all in the same room. So when someone is taking a shower, it steams up the room and makes the mirrors above the sinks unusable.
The AKL doesn't have HDTV's in the rooms which is a big advantage because the Polynesian doesn't feature HDTV channels on those TV's. When you're watching standard def TV on an HDTV it looks a lot worse than on a standard TV. On this last trip we stayed at French Quarter for a couple of days then went to the Polynesian and I missed our TV at the French Quarter because it looked so bad on the HDTV at the Poly. Now most of the time TV isn't that big of a deal, but if you're staying at a deluxe resort you want to spend more time there to relax.
The bus transportation at the AKL has been fantastic in my experience. Buses usually flow through there more frequently than what I've seen at any other resort I've stayed at. Also you don't have to worry about sharing buses with any other resort. Kidani Village is an added stop now, but it's so close, it is almost negligible. It took us 45 minutes to get back from the Animal Kingdom to the Polynesian this trip. We went to Blizzard Beach then the Contemporary and then finally to the Polynesian. Having the TTC close to the Poly is very nice if you are in Rapa Nui or Tahiti (which we did), but a lot of the rooms at the Poly are a big hike away from the TTC and that's the only way to get to Epcot.
I know I'm comparing the AKL and Poly a lot, but those are the two Deluxe resorts I've actually stayed at. If the Poly and AKL were the same price, I would always choose the AKL.
Notice I didn't mention the animals once. They are nice, but it is far from being the most important aspect of the resort. I would NEVER pay more for a Savannah view room there. There are a ton of viewing spots all over the resort. I think the prices they charge for the Savannah view rooms are one of the biggest rip offs at WDW, but I can see why they do it. If you don't know any better, you would think it is the only reason to stay there.
If I couldn't stay at the AKL, the Boardwalk would probably be my 2nd choice.