i never read manga too actively, instead i just had tachiyomi installed with some backlog downloaded and it was fallback entertainment when no network connection, bored by network connection, or just otherwise wanted to. therefore i've been reading the same things for a very long time, just a chapter at a time
Yokohama Kaidashi Kikou - a calm story about a robot who runs a coffee shop and does errands in a post-apo world. incredibly well drawn, with beautiful backgrounds, and a slow story about the small things in life in an ending world. recommended to me by funtime, would also recommend myself
GA Geijutsuka Art Design Class - a cute comedy/SoL 4koma about girls studying art. it's pretty funny, has great illustrations, and has a bunch of interesting information about art and design thrown in as well, simply because it's being discussed. also kisaragi cute
i've also finished
Sayonara Zetsubou Sensei this way, it's pretty good (although i didnt like the anime and i dropped it). also i've read a bunch of Don Rosa works thru tachiyomi like that but that isnt manga is it