my favorite manga ever is Sanshirou no Jijyou. it's never popular enough to be made into anime, so really few people outside the east asian know about it. if you google it, hardly anything related to the series come up, in fact.Quoting Sycophant (view post)
a more well-known examples are city hunter and maps. those three are like the trinity of my manga religion. (3x3 eyes used to be here, but was demoted because of the suckfest near the end.)