Eren Yeager was a conceited, petulant child who did the rumbling simply because he was scared of the complexity of the world and dealt with it in the only way he knew how. Tatakae.
That's why I think he did the rumbling. Not because he was forced to by visions of a pre-determined future, not for the sake of paradis island, and not even for the sake of his friends. He gives Armin all those conflicting reasons at first because he simply doesn't want to admit the small, twisted truth inside. While he knew deep-down that he was an idiot who got too much power, he found it easier to tell the world that he did it for paradis because he's a half-assed, titanic, ego-driven nightmare.
Eren was always a child who felt a sense of existential dread at the prospect of being oppressed. His dread manifested as anger against Armin's bullies, Mikasa's kidnappers, the walls, the titans, and finally the world. He always had this core belief that you had to fight in order to take your freedom; that if you weren't the one holding the knife, you were the one who would be at its mercy.
In other words, he couldn't bear to live in a world where he couldn't control everything. He wanted to destroy it to soothe his own panic, but lacked the intellectual courage to admit it to others or even himself.
When those truths finally caught up to him, he didn't grow. He chose to hide behind a wall of excuses.
He claimed that he had to follow his visions of a deterministic future. But the truth is, he didn't stop to question it because he wanted it deep down and it felt easier to think that he committed genocide because he had to and not because he wanted to. It's only a self fulfilling prophecy because he wanted to fulfill it. That's why he saved Ramzi. He's half-assed. He wants to rumble it all away but the hypocrite can barely deal with the guilt.
He claimed to do it for Paradis. This was the easy reason to give to the world and alleviated his fear of being ordinary. It wasn't because he was scared of the world you guys! it's because he's a freedom fighter who initiated the rumbling to save his homeland out of fated, tragic necessity!
He claimed to do it for his friends. This is the reason he wanted to give to his friends so he doesn't seem like a devil to them at least. Of course, our boy Armin sees through this immediately. That couldn't possibly be the true reason since he must have known he would have forced them into danger to just to stop him.
Even if he wanted to end the titan curse, Zeke's plan was indubitably better way to do it, which is crazy to admit in and of itself. There were other paths forward, he simply refused them because they did not center on his own desire for absolute control. And being able to say "look, at least i ended the titan's curse so my friends can live long lives!" is simply a weak attempt at making his own violence appear less senseless.
That leaves only one honest answer. He did it for himself. He had every chance to stop but he chose not to.