Who´s more violent and why?
Joker kills with intent. It may be the most psychotic intent, but he doesn't just wake up and kill everyone. He wants something, even if it's trivial.
Bullseye is the least violent, he enjoys killing, but he takes the utmost premeditation in doing so.
Sabretooth kills to quell a bloodlust. He also thinks it's fun. But he often uses his slaughters for a purpose, to lure someone out or just to get revenge on something.
Carnage doesn't really care. He just kills people. He doesn't set up elaborate traps for his archnemesis with people's lives on the line like Joker, he'll kill them way before it gets to that.
When you're fighting Bullseye, he's fighting you. He'll ignore passerby's, or maybe use them to his advantage. When you're fighting Joker, you're trying to figure out what he's up to. Maybe people die, maybe they don't, but he wants you to play his game. When you're fighting Sabretooth, he will concentrate on you if you're annoying enough.
But when you're fighting Carnage, you could absolutely lay into him, and it's entirely possible he'll completely ignore you and continue biting heads off of random people.
@Strider92: honestly i was thinking more at that 2nd definition you gave
Then yeah Carnage. Joker just likes to you to play. Carnage just couldn't give a damn. He slaughtered a ton of people in Houston recently just for the lolz of it. Joker normally has some kind of goal Carnage doesn't.
I agree with pretty much everything in this thread, though I think Sabretooth pulls a close third. He could theoretically go completely berserk, after all, which would trump all 3.... that's not my main reason for supporting him though obviously, merely a thought. I do believe Sabretooth's merciless animalistic savagery is a worthy contender for Joker's deadly mixture of mental and physical brutality and Carnage's relentless bloodlust
Carnage will pretty much walk into a bar and kill anyone he sees without any plan or motivation other than the sake of killing. While the Joker is violent, he often wants attention from Batman, I can't imagine Sabretooth going on a mass killing spree just for the sake of it and Bullseye, although he enjoys his work, is often in it for some other motive.