There are very few superheroes and superhero teams that are consistently popular from decade to decade. Most characters are flashes in the pan, never rising above bit players in the shared universe. A slightly more prestigious group are the characters that rollacoster between extreme heights of popularity (useally when a star writer gets on the book) and extreme lows. To me their are really only three or so franchises in the whole superhero genre that are consistant sellers.

Batman, Superman, Spiderman. Most of the other big characters that you can name are really in the rollercoaster category.