I think Cheetah presents a problem in terms of visuals. Werecats read as less powerful than gods. Having Cheetah go toe to toe with Diana is a mistake. If this is supposed to be Diana's intimate villain, that is, the one who was a history lover and a friend and then is corrupted by mystical power, then let her be that. The knock-down-drag-out fight was actually one of the weakest parts of Wonder Woman. Trying to force the idea that cats > gods down the audiences throat isn't going to take, it's going to feel inauthentic. That's okay, villains don't have to be ones that go toe to toe with heroes. Joker wasn't. Loki wasn't. That's what makes them archenemies, they're not primarily physical foes, though they, with planning, do become physical threats.
It also would be a mistake to just do Cheetah on her own. She carries the people-into-animals theme right alongside Circe, and so even if Cheetah doesn't get her powers directly from Circe, Cheetah needs a villain around who can go toe to toe with Diana, Circe needs a personal villain around, Cheetah can lead an army of Circe's man-beasts. I'm not saying it writes itself, but, there's no better secondary villain in WW's gallery for either of these two, and both need a backup villain, just like Joker did, just like Pierce did.
Alternately, you're basically saying you can do Circe OR Cheetah, because after fighting Cheetah, you can't really do ANOTHER movie where Diana fights werepeople, without communicating that that's the type of people Wondy fights in the present, maybe since all the gods are dead? Weird.
I think the Circle works much better for a threequel. They literally are all about coming full Circle on Diana's origin and home.