I am curious to see what other people think on the matter.This is not a question on if they are a well designed character or who is your favourate it is who is more evil. Doesn’t make much sense sorry.
First, I’d like to thank you for posing such an interesting question.
Now, my answer really depends on how you would define ‘evil’ or ‘good’ in the context of your question. Are people in the Baccano universe good because they abide to local laws? Is a person evil because they have killed an evil person? Consider Elmer Albatross, who doesn’t necessarily do evil things but comes to the aid of people who could be considered evil on a regular basis. Is he guilty by association?
To make this an easier choice I will define an evil person as “an individual who by their own will violates the law”. Ladd Russo and Claire Stanfield, along with the majority of the Baccano cast, fall into these parameters. So who is more evil? Definitely Claire. Both Claire and Ladd kill people. That’s pretty evil. They both kill people for money, so what’s the catch? Ladd started killing people because he got the urge to do so. (Forgive me I can’t remember which, but) In one of the books we learn that Ladd came from a normal, middle-class family, and wasn’t abused at home or molested by an aunt or anything that would usually be the beginnings of psychotic behavior. But he still became a killer. He joins his uncle’s organization so that he can kill with less risk of being arrested and jailed. And he curbs his ‘appetite’, his urges, by using discretion - taking jobs from Boss Russo, and of those preferring to kill people who think they are very safe. I think Ladd’s situation can be classified as a mental illness. Outside of his control like a cancer, or appendicitis.
Claire’s motives for killing are only slightly different. He is orphaned while a child, but gains a new family. Then he leaves them and joins the circus. Earning enough money to support himself and to send money home to the Gandors. A bit before the 3 brothers start running their family, Claire becomes an assassin, killing for hire pays pretty well. Next, he becomes a train conductor - a job that he really really loves. By this time the Gandor brothers can support themselves. It was sweet of Claire to look out for his family like that, but he made a conscious decision to start killing people. Claire is completely responsible for his actions. He is of a sound mind, aside from his solipsist philosophy, and he has no trouble controlling his actions. In fact his career history required him to have an incredible amount of control over himself.
In conclusion, Claire and Ladd are both evil, yeah. But Claire is the greater evil. Claire makes a choice every time, to kill or not to kill. Ladd, already cursed by his own nature, can only make a choice of who to kill.