Hisoka only killed the puppets that tried to kill him. All of Hisoka's victims were either asking for it (puppets trying to kill him, hunter exam candidats trying to mug him) or are strong people that chose a life of danger (people that can take the abuse). People like Gotoh and Kastro are fighter. They fought and they lost. They aren't victims.

Hisoka didn't even take part in the York New massacre, I remember him gazing in disgust probably thinking "these weaklings (the mafia) aren't worth my time".

Chrollo on the other hand has never fought a strong opponent by choice. He only seems to target helpless opponents like the Kuruta, the mafia, the princes of kakin. In the Kuruta massacre, the phantom troupe started torturing and killing the children and women infront of tge adult men in order to enragd them. And the fact that Chrollo can feel the pain of losing a loved one make it 10 times worst. Meaning that Chrollo knows what his victims feel and he still does what he does anyway.

Hisoka might have a complete disregard for other people's lives, but he also disregards his own life. So in a way he treats people the same way he treats himself. Chrollo on the other hand is fine with killing other people's loved ones, but cries when someone does the same to him.

IMO Chrollo is 10 times worse than Hisoka.