Using manga categories as examples (shounen, shoujo, seinen, josei, etc), I don't think there's a single manga that will cater to everyone. Not everyone will like fights to the death, or thrillers, or romance.
For example, I make a girl's love comic set in space (despite my main influences being shonen and seinen mangas lol...but i'm making a shoujo ai) I have no clue what the demographic of my comic is, but some people seem to like it.