Cell wasn't shown to take pleasure in killing people like Vegeta, Nappa or Freeza. He did it to achieve his perfect form but he did it quite efficiently (kinder may have been to kill them and then absorb them, maybe. Not sure which would be worse) - snook up on them and absorbed them without taunting them or enjoying their suffering. Freeza and Vegeta were also shown to kill typical children (not Gohan who's a powerful combatant).