My inclination is to say the Shooter/Swan ADVENTURE COMICS run on "Superboy and the Legion of Super-Heroes."
Truth be told, I don't think many works on comics history have really gotten across how unclassifiable the Shooter "Superboy and the Legion" was. The entire series was in a strange, in-between state: with elements of the Weisenger worldbuilding and gimmick-centered stories, and the Schwartz obsession with science fiction. It was also an in-between book, moving between DC-style old-school heroism, and Marvel style subtle "hip" dialogue and "counterculture" vibe, consisting of evil grownups and sympathetic monsters. How many stories in that period were about mind-controlled grownups that just didn't get it? The Mantis Morlo tale was explicitly about pollution. "The Unkillables" had peace prove to be more valuable than war.
The characters spoke in a variation of the Stan Lee-patented Marvel lingo, like Brainiac 5 saying "Chuck the chatter! Listen to that guy's spiel!"
It was very, very different from the "Jumping Protons!" future-talk the equally visionary Ed Hamilton gave them.
(Incidentally, am I the only one that noticed how similar the Ed Hamilton dynamic, where Dream Girl was visibly leched after by the entire male roster - is similar to the early X-Men?)