Merged the topics since they're basically the same thing.
Aside from my previous post, I could've said 20th Century Boys if SHC hadn't already. A Kongo Bancho adaptation could also be good if done by a studio like David Production due to how much of a love letter it is to older Shonen (and is far better than its mangaka's current work). It would also be pretty interesting to see Ichi the Killer and Homunculus translate over to animated form.
Eden: It's an Endless World would be pretty interesting to release in the current era given how many themes and topics it'd explore that'd trigger the easily offended snowflakes. I could also mention Onanie Master Kurosawa, though the ending is quite disappointing and overall it's just a mini version of Welcome to the NHK. Real would also be another one worth mentioning if not for it having no part that could act as a good cutoff point before the hiatus would force it to end (assuming Inoue were to go back on his no anime policy for his works).
As far as individual arcs, I'd want the Vinland Saga anime to adapt Farmland and maybe the current arc (at least as a Season 2), so that the anime can actually cover Thorfinn's character development, not to mention the pacing would be a lot better in anime form. Also a remake of Berserk's Black Swordsman, Lost Children and Tower Arcs without ClanGI (or at least Vinland Saga's smooth transitions between 2D and 3D), though avoiding adapting Berserk altogether seems preferable at this point.