The only person I could think of that I would put over her as a heel is The Miz. Miz probably gets the edge because of his ability to talk on the microphone, but Charlotte isn't that far behind for me.
WWE does a lot of things wrong with the women, but their booking of Charlotte as a character has been exceptional in my opinion. She's dominant in the ring and knows it too. She doesn't need to cheat to win, which is why she has so many clean victories under her belt, but she does it anyway. The way she carries herself is phenomenal - if you never watched the WWE beforehand, you would know immediately she isn't who you are supposed to be rooting for. It was nice to see her attacking Bayley after the match because she "stole her moment".
This is the kind of champion I wish Kevin Owens was. He comes across as more of a coward than anything, which doesn't suit K.O.