One thing I like about LoGH is that antagonists don't do random unjustified evil shit just so we can never support their argument and have to see them as truly villains.
For example people like Star Wars, but you can never defend Empire or say "Rebels were a bunch of terrorists Empire wasn't half-bad", because there's the whole blowing up a planet and killing kids thing so they're undefendable to normal people.
On the other hand the only questionable thing Reinhard did is that letting those 3 million civilians get nuked, and this mistake haunts him forever. Terrans are just following their religion, and Phezzan only thinks of its profit. Yang fights for a corrupt democracy because he believes even a corrupt one is better than the alternative. No one is evil for the sake of being evil.
Rudolf is the closest character made to be seen bad I guess, but on the other hand everything was degenerate before him and his Empire stabilized space for a while.