well, to me, that is actually even harder, you know
there are already 80+ completed titles that I recorded on my myanimelist that I gave a score of 9/10 and 10/10
I would love to also recommend those that I scored 8, but then that'll make it 250+
so if it is just any good completed titles,
well, you can try pick one from the
top scored completed manga from myanimelist
I've read almost everything listed, and each one is worth recommending
now then, if I narrow that list down to the only first 10 titles I think ended well
(without or minimal loose ends, no open interpretation, etc.,
and more importantly it satisfies me, and I like it)
then I'd say: Slam Dunk, FMA, ReLIFE, Dungon Meshi, Chihayafuru, Kenshin, The Fable, Hokuou Kizoku, Kimi to Tsuzuru Utakata, and Ohayou Ibarahime
I said 10, but when I see the next item, and I really want to write it down too
but then the list will never end