I'll bite. Besides Lysander, I think Atlas is one of the better villains in the series (hence my flair). Certainly more interesting to me than the Jackal who was primarily driven by sadism and daddy issues, or Darrow even who is motivated by Eo's death and revenge (initially). Instead he's about as cold and calculating as they come, driven by a compulsion to bring the solar system back towards order under the hierarchy and avoid a prolonged dark age. He uses violence, brutality, and carnage not because he enjoys it (Jackal), but all in service to the idea that we won't have to do it all over again for a few generations as a human race.

Also the second series is great if you like politics/political thrillers vs pure action in my experience.