Personally it would be claymore, often hailed as a female centric berserk.
A story about the lowest class of a generation of engineered superhuman woman fighting monsters to save humanity.
The art gets better and better as it goes on, with stunning panels everywhere(example below).
The intrigue struggle and strive the characters go through is a stellar example of simple yet effective storytelling.
Oyasumi Punpun (Goodnight Punpun) is a cross-section of a boy's life, who was raised in fucked up circumstances and showcases the horrific consequences it can have going into adulthood. Be warned, it qualifies for nearly every trigger warning under the sun: >!depression, suicide, emotional abuse, a wide range of violence, arson, sex crimes against adults and minors, other borderline sex crimes, parental abuse (physical + emotional), domestic assault, neurodivergence amongst children and the behavior/language that entails, cults!<...
It's a great 'slice of life', but it is truly disturbing. And it's disturbing in a way that no amount of gore and violence could achieve...because you watch Punpun grow up, and he feels like someone you may have known or may have been. You'll have so much sympathy for Punpun...and he will test that sympathy.
Oh, and the art is phenomenal. The stylistic choice to render the main character and his family as cartoonish birds was brilliant, and the art in general is fantastic.
Alternate recommendation that won't sacrifice your emotional well-being for the sake of good storytelling:
One Punch Man is a shockingly good read. It's not exactly an earth shattering narrative like Goodnight Punpun, but it is equally a one-of-a-kind manga/anime.
You wouldn't think a story where the protagonist is effectively invincible and seemingly infinitely powerful would be interesting, but they do A LOT with the premise. The action is great, but the side-characters really form the meat of the story, and there's a lot of genuinely wholesome, funny, and sometimes sad moments.
The anime is very faithful to the manga, so I recommend them both. However the anime is very far behind in the story, so you'll inevitably end up reading the manga if you enjoy the story.