I think there is more than one kind of evil. Angelus represented the sort of conscious malevolence, cruelty and will to power that the word most usually evokes. But there’s also the evil that comes from just not caring. I think S6 of BtVS showcases this later form. Warren, Andrew, Jonathan and junkie!Willow just want to have fun, they don’t even think about who might get hurt, althoughWarren (like William) may also want to settle scores with those who used to belittle him. In Tabula Rasa Spike shows no bloodlust but in the very next episode he sets out to kill a girl just to make a point in an argument with Buffy, someone his victim has probably never even met. In the sense of not caring he is more evil than other vampires because, being fearless and out to prove a point, he’s killed more people and still doesn’t care.