It is mostly a matter of personal preference.
The theming of AKL is very unique. I have slightly mixed feelings about the animals. I enjoy watching animals in my backyard immensely, but that's because they are living life the way they are supposed to live. They come and go as they see fit. And well one of the critters that comes near my house is a hawk, and it hunts. The squirrels forage. Captive animals never have an opportunity to hunt or (really) forage. Their lives aren't interesting to watch; it is sad their lives are so dull. So personally, I didn't spend much time watching them. If WDW had a full nature reserve, that would be far more interesting. For animal viewing, the Everglades NP/Big Cypress NF are far more interesting, IMO. (3.5 hours south of WDW) Or this time of year, maybe visit one of the places where wild manatees congregate. (Both of FL's coasts, drive varies but Tampa is one of the closest at 1.5hours away.)
Beyond that, the theming of AKL is great. A plus of the pool- this time of year- is that it is close to the hotel. If the weather is a little cool for swimming, you don't have far to go to get indoors. I also have always liked the food of Boma, and the aroma in the lobby.
Both are bus only transportation. If I was staying at either, I would tend to want to have a car. Overnight parking at Gran Destino is a little less. I want to say $15; while AKL is - I think - $25/night. (Not 100% certain of the current rate, and it is WDW so it could always go up before your dates.)
Gran Destino is super but walking the whole of Coronado takes some time. AKL is more compact, unless you get one of the rooms at the far end of the hallways. If you just plan to eat/stay in the tower, getting around the GDT building is quick/easy. The walk to the pool was a little ways, but not too bad.
Gran Destino is newer. Not super-duper new, but only a few years old. The theming and decor is really pretty, and we really liked the room and glass door shower. My most recent stays at both though were pre-pandemic, so I'm not super up do date on current menus/staffing. When we stayed at GDT staff was great.
