I feel that Animal Kingdom is pretty unbeatable in terms of pure aesthetic beauty in Florida. The sheer amount of details that can be found if you're willing to look hard enough is astounding, and Pandora has only helped its case. The way it is designed to be "explored" as opposed to just walked through I think puts it a step above the other choices.
I could see an argument for Epcot as well, though Future World drags the beauty of World Showcase down quite a bit. I could see when (or if, at this point) the vision of Epcot 2.0 comes to fruition it becoming the most beautiful park in the state. As of right now, it seems like a mess of construction walls, not the prettiest sight. Interestingly, with both of these choices, the biggest issue I have with them is their lack of rides, with Animal Kingdom needing more supporting rides and Epcot needing more headlining rides.