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.
Of course! If not for the story, at least for the art it's totally worth it. I haven't seen the anime (Yet), but I understand there are some differences between the two works, might be interesting to see what they are.