There's a lot that's not talked about and mental health is one that is frequently swept under the rug and ignored. Joker gave a first person perspective of how a psychosis patient may view things and some of the difficulties people with those problems face. Joker literally bottles it up until there's not enough space and he unleashes it in a violent way that's an exact regurgitation of his environment. There's still parts of that film you still aren't sure are real or were figments of his imagination.
Logan was great but didn't have that. Logan was about Redemption and trying to find meaning in a world without any. Even if it had to be superficial (in the case of the little girl). Amazing storytelling but Joker was far more culturally relevant than Logan.