It's hard to beat the AKL. It's new, has a great pool, great restaurants and animals right outside your balcony. Simply saying that you can see animals outside your window understates the benefit. You can see animals all over the resort. There are great viewing areas at Arusha rock and all around the pool area. Plus, there are viewing areas throughout the resort. Simple stairwells often become great spots to observe animals.
The one negative about AKL is its location. It feels isolated, especially if you are used to staying at one of the monorail resorts. You are close to AK, but that's about it. When we stayed at the AKL, it was for 4 days of a 10 day stay on-property. The 4 days we were at the AKL, we visited the AK twice, downtown disney and explored the resort. When we transferred to the Poly, we hit MK, Epcot and MGM.
If I was staying only at one resort, for me it would come down to whether I wanted to trade the convenience/location of the WL for the uniqueness of the AKL. As great as the AKL is, if it was for my entire trip, I'd choose the WL.
Hope this helps.