I personally voted for Krell, mostly because while I haven't watched RWBY (and I don't intend to, it doesn't sound like something I would enjoy) I have seen some clips and Cinder was abused pretty horribly by her adoptive mother and sisters and she even cries in the present when she remembers the abuse she suffered. Meanwhile, Pong Krell has no Freudian Excuse as far as we know.

I've watched RWBY and I agree that Krell is worse than Cinder.