I mean, I wish we could have BOTH!!
. Pandora is my favorite section of any Disney park and I might give it the slight edge to the Beastly Kingdom because the land itself looks more original (I know Pandora is based on an IP, but the aesthetics are more unique whereas the concept art for Beastly Kingdom — while pretty — looked a lot more like generic fantasy and would have clashed more with the overall look of Animal Kingdom). I will admit though, a "Beastly Kingdom" is a more broad concept that would give Imagineers more freedom to expand and experiment than Pandora will.
For instance, the original concept of the land had the Dragon Tower, Loch Ness Landing Restaurant, The Quest for the Unicorn, and the Fantasia boat ride. Since the theme of the land is mythical creatures, I could have seen this land adding in attractions and rides based on movies like Hercules (Pegasus and the Hydra would be right at home), Angelina Jolie's Maleficent (the Moors creatures) and Raya and the Last Dragon (Sisu and the other dragons).
I think elements of Beastly Kingdom can still be used. Maybe there could be an expansion to Asia that has a heavy emphasis on Asian mythological creatures (including a dragon). It could use the same general ride concepts as the Beastly Kingdom, but make the aesthetic Chinese instead of medieval Europe.