Jojo's Bizarre Adventure is full of crazy characters. Hirohiko Araki's manga hit has always been true to its name, after all. The protagonist family of the Joestars is known for their charisma and strength of will. But with such powerful protagonists, there need to be equally powerful villains.
While the Joestar family is often praised for their ability to move people, villains can do it as well. Charisma is often said to be the largest antagonist's most powerful quality. These characters are looming intimidating presences that are larger than life. And with that presence, their words brought their larger-than-life insanity into the world in quotes.
Dio Brando
"I Reject My Humanity, Jojo!"
Dio Brando is the invader who stole Jonathan Joestar's life. He devoted his entire wretched existence to making Jojo's worse so that he could succeed in place of him. But Jonathan never broke, despite all of Dio's machinations and plans. Dio would say it himself;' it is like human plans to go awry, so he could never defeat the noble apex human Jonathan.
This is why Dio rejects his humanity, donning the Stone Mask in the iconic scene where he makes this declaration. It's a chilling and dramatic declaration that shows his desire to rise above everything. Not only that but also his hatred of Jonathan is apparent as a direct challenge to his humanity. Dio becomes a vampire, looking to stand at the top of the world with this frightful quote. Dio's ascension is a big reason to read Part 1 of Jojo's Bizarre Adventure.
Kars
"Don't You Wish To Tame The Sun!? Don't You Wish To Dominate Creation!? Don't You Wish To Not Fear Anything!?"
Kars was the leader of the Pillar Men, a group of proto-humans who used to dominate the world. Or more specifically, he's the leader of the surviving Pillar Men. There used to be far more of them until he and his compatriot slaughtered them for not agreeing to his plans. This quote comes from his beseeching cry to his fellow Pillar people to agree to his plans before he killed them.
He wanted to use the Stone Mask to become perfect beings. But the culture of the Pillar Men was complacent and deemed his desires unnecessary. Kars also wanted to stand at the apex, but differently from Dio. He wanted to stand above all things as the highest lifeform on Earth, not above human society. He wanted to destroy all weaknesses in himself.
DIO
"Invulnerability! Eternal Life! Stand Power! Here Lies The Proof That None Shall Surpass The Mighty DIO!"
Dio Brando was the antagonist of Part 1, but when he returned in Part 3 he was now DIO. He had become a dark messiah-type character in the hundred years he was away. His name could no longer be spelled lowercase, and characters would revere him like a god. This is the DIO that had boundless charisma and is commonly thought of as Joestar's biggest enemy.
The vampire maniac also came with a new great boon; his stand ability. With this, he grew even more powerful than he ever has before, also becoming even cockier than he ever had before. He thought of himself Over Heaven as he declared this line, after dispatching Jotaro and full on a glut of Joseph's blood. However, despite his grandstanding, he was incorrect. He did not have the first two, as he was about to learn from a still-alive Jotaro Kujo.
Yoshikage Kira
"For Me, It's Not Really About Winning Or Losing. I Just Want To Survive. I Want A Peaceful Life. It's Just That It's In My Nature To Kill."
Kira was a big change from the previous villains. Yoshikage Kira didn't want to take over the world, but he just wanted to be left alone. Fitting of what a departure he was an antagonist, his quote is simply an explanation of his motivation. Of course, he wouldn't be a villain if he also wasn't an unrepentant murderer on top of that.
He's a serial killer that would cut off women's hands and violently murder witnesses. So his pleas for "just leave me to peace" kind of fall flat. But it's that entitlement that makes him such an interesting antagonist, as he isn't interested in rising above society like the past villains and makes him a unique underrated anime villain overall. Yoshikage Kira puts it best himself, he just wants what's in his nature.
Diavolo
"Only The Results! In This World, Only The Results Matter!"
Diavolo represents an odd middle point between Kira and DIO. Like Kira, he is absolutely protective of his identity and goes to ridiculous lengths to protect it. Unlike Kira, he still wants to rise above society and rule supreme as a mafia boss. This contradiction is why he has such an end justifies the means quote and worldview.
Diavolo's confusingly bizarre Jojo Stand ability, King Crimson, allows Diavolo to bypass events and only experience the results. This is representative of his contradictory wants of anonymity and total power. He can't have both, but he thinks that just focusing on the results will get him there. Part 5 in general is about how the journey is greater than the destination, so having an antagonist who believes the opposite is thematically strong.
Enrico Pucci
"Humans Should Spend Their Lives Trying To Attain 'Heaven.' That Is The Beauty Of Humans."
Father Enrico Pucci is one of the most soft-spoken and eloquent villains in the Jojo world. Anime only fans will get to enjoy many further speeches from the priest as new episodes of the anime are released. While his worldview has been corrupted by DIO, he remains pious. He has a fixation on "Heaven," by which he means a paradise for mortals, not specifically the Christian idea.
Pucci greatly respects humanity, unlike the previous antagonists who thought themselves above it. He thinks the capacity to be moral is what makes humans great. Somewhat ironic given his status as a villain, but Pucci is earnestly seeking a way to carry out what he believes is right. He's not always nice or kind, but he is striving for his view of paradise on Earth.
Funny Valentine
"The One Who Took The First Napkin Determines Everything."
Funny Valentine is the main antagonist of Part 7, and as it hasn't been animated spoilers will be minimized. Funny is a politician with a past as a prisoner of war and one of Jojo's best characters. He's a high-class man with heavy ideals, delivered in that strange Jojo fashion. The above quote comes from a monologue about his motives, which is explained in a metaphor of napkins at a dinner party.
It's an odd metaphor but it boils down to this: people don't do things arbitrarily, they tend to follow precedent. If you take a certain napkin first at a dinner party, the rest of the guests will follow. Valentine's chief motivator is to be the first person to take the napkin; to be the person who sets the precedent to be followed. Valentine wants him and his country to be the leader of the pack.
Jojolion's Antagonist
"Defeat Or Victory Mean Nothing To The Rocks On Top Of These Cliffs."
Not only has Part 8 not been animated, but it also only finished its run last year. As the identity of its main antagonist was a mystery for most of its run, the character's identity will be hidden here as well. But like Kars from Part 2, this character is extremely long-lived. This also manifests in indifference to the main characters, but in a different way.
The main villain of Part 8 is heavily involved in the affairs of humans, unlike Kars. Instead of viewing themselves as above humanity, they seem to want to succeed besides humans. But he still has advantages to leverage over their human opponents, like their long life. Comparing themselves to a rock, they boast that humans can't possibly affect them.