Well now I want to know what these four are. I'm genuinely curious and would appreciate the recs!
Nothing special unfortunately, they're mostly already well known. In no particular order:
Berserk obviously. Scope, ambition, richness of themes and characters. Golden age arc is incredible, but everyone knows about this.
Blame! Another fairly popular one, if slightly more niche. Atmospheric, meditative quiet scenes interspersed with intense violence. Thematically abstract in a way that it can be applicable to all sorts of real life experiences.
Nausicaä manga. By Miyazaki himself. Has an ambitious scope to rival Berserk that extends far beyond its anime adaptation. By the end explores moral extremes of human nature to an extent I've never seen before.
Freesia. Lesser known. By far and away the most tightly written manga I've ever encountered. Set up, payoff, character and thematic arcs, social commentary, all woven together so tightly it's made multiple rereads even more enjoyable than the first.
Be warned that all of these have pretty graphic themes if you're the squeamish type, though I doubt that given the content of the manga on this thread.
I think by comparison Maria no Danzai is more akin to popcorn media. Fun while you're reading it, if that's what you're into, but it has little "nutritional value," not so much that'll stick with you once you're finished.
Edit: I hope you find at least one of these you didn't know about and enjoy it!