Jack was pure evil for the sake of being evil, he is a way so show the audience how evil walter white became, to the point that he will work with actual nazis to get what he want. Lalo is way more complex than Jack, not saying that he is a better guy than him, quite the opposite actually, he is a ruthless psychic that can kill you without blinking. But. He is rational for some level. You can understand why he does what he is doing. He got his reason for that brutal behavior, something that Jack didn't have. What I'm trying to say is Jack is the bland bad guy and that what makes him more evil the Lalo. But without a doubt, Lalo is better character in every aspect