[Kim]

Ehhh, you're judging the two characters against each other based on their accomplishments. Porky was manipulated by a Devil metaphor and also given a time travel machine by that entity. Porky was a selfish, immature child manipulated by forces far greater than him and given great power he was not adult enough to handle by them. No longer bound by the rules everyone else is, he did a great many evil things, but he also never had the opportunity to grow up and become a better person.

We also see that much of Porky's horribleness is a result of his childhood in other ways. He had no real friends, the Devil metaphor pitted him against the only person he actually considered his friend, his father beat him. Porky had a shit childhood. From what I recall, Cartman's just a spoiled shit.

I vote Cartman is worse, because the only reason Cartman hasn't done what Porky has or worse is because Cartman simply doesn't have the ability. Cartman doesn't have being directly manipulated by the Devil as an excuse. Cartman's mother, from what I recall, isn't physically abusive towards him. Cartman's a terrible person with less excuses for it and who is only held back from being worse by the lack of opportunity to be worse.