Tell me which one

I think crimson is the worst one out of All of them

Unfortunately you didn't show Peter and Lois Griffin who seem much worse than these

Well, all of them, they're all pricks.

As for who's the biggest one...I'd say Crimson. The others at least don't want their children to die from what I read. Crimson abused Moxxie for years, made him see that he killed his mother, molded him into a hitman (if a moral one), never bailed him out of jail, forcefully married him off to his creepy ex, threatened to kill him, and now seems to be ready to fulfill that threat.

All of them, including Butters parents, Ozai, the scientist from Fullmetal Alchemist and Hulk's dad

Okay, I do have to ask, what the hell did Odalia do to her daughter?

And also Heinz Doofenschmirz's parents. They're also terrible

Gendo used to be a terrible parent though idk if he counts now

Heinz Doofenshmirtz’s parents are horrible parents. Heinz suffered an tragic childhood filled with abuse, neglect, bullying, and abandonment. His parents abandoned him at the hospital after birth, he was forced to be a gnome after his parents’ gnomes were repossessed, Heinz was bullied during his entire childhood, he was forced to wear dresses for a year after his younger brother, Roger was born, Heinz set up his own 5th birthday party at a pizza restaurant which no one showed up and the mascot taunted him, his parents preferred Roger who is more attractive and athletic than Heinz, his only friend was a balloon which Heinz earned after working at a fair, he was raised by ocelots after he was abandoned, he loses competitions to a baking soda volcano, his social status and love life were horrible as well and his inventions and schemes always backfire on him. Despite his tragic childhood, he got married, had a daughter who he loved dearly and Heinz doesn’t want her to suffer the same way he suffered during his childhood. Sadly, his marriage didn’t last long which leads to a divorce.