Milady
Of those I'd call my enemy, I'd say Milady upsets me the least.  I know it sounds strange, but it's true.  She's more or less the power behind the Ebene, from what I understand, and a cunning, manipulative warrior, but she seems to come by it honestly.

Milady, for all her faults and wicked intentions, never seems to make much of her attacks personal.  She is fighting against a faceless entity, just as we are.  This is not to say that she isn't well informed.  She knows us, something that can be a little more than unnerving.

I have yet to figure her out, completely.  It seems to me that she's hiding behind Zelazny, but really could easily dominate the Ebene.  My question is why she doesn't stage a coup.  I suppose it's because she's focused on destroying us right now.  I have yet to see if there is any personal alligence to the Ebene, or if that's just furthering her own gains.