Originally Posted by
Comic-Reader Lad
You say you don't want "long arcs," but in the 1980s, long arcs weren't really done a lot unless they were a separate miniseries like Watchmen.
It's hard at this point for those of us who read comics in the 1980s to point to a specific issue. We really just remember a certain creator's run for the most part. Issues within a great creator's run are generally all worth reading and even if it's not a "long arc" in the sense that it's all one story, elements of earlier stories often do get touched upon in later ones, so forgive us if we do just rattle off swaths of issue numbers instead of just a single one or two.
Since DC really hasn't been touched upon, I'll add a bunch here and list it by character:
SUPERMAN (pre-Crisis):
(1) Superman Annual 11 (1985): Alan Moore & Dave Gibbons, before they teamed for WATCHMEN, created the classic "For the Man Who Has Everything" story featuring Superman, Batman, Robin (Jason Todd), and Wonder Woman vs. Mongul. This was adapted in an episode of both Justice League Unlimited and Supergirl.
(2) Superman 423, Action Comics 583 (1986): Alan Moore writes the last pre-Crisis Superman story, "Whatever Happened to the Man of Tomorrow?"
SUPERMAN (Post-Crisis)
(1) MAN OF STEEL by John Byrne (1986) - Published soon after Alan Moore's story above, this lays out the backstory of the post-Crisis Superman. Really, any trade collection of post-Crisis Superman from 1986-1996 is worth reading.
BATMAN
(1) Batman 404-407 (1987) - The classic post-Crisis origin of Batman by Frank Miller and David Mazzuchelli -- "Batman Year One."
WONDER WOMAN
(1) Wonder Woman 1-24 (1987-1988) - George Perez pencils, plots, and eventually writes the post-Crisis Wonder Woman. The first 6 or 7 issues show her post-Crisis origin and journey to man's world to fight Ares (in the 80s, not World War I like the movie).
JUSTICE LEAGUE INTERNATIONAL
(1) Justice League 1-6, Justice League International 7 (1987) - begins the legendary Keith Giffen/JM DeMatteis/Kevin Maguire run on the title. Superheroes with a sitcom bent.
LEGION OF SUPER-HEROES
(1) Legion of Super-Heroes 290-294 (1982) - Paul Levitz and Keith Giffen give the Legion perhaps its greatest, and most famous, story, "The Great Darkness Saga." This can be daunting for someone who never read the Legion as it features every team member and pretty much every supporting cast member who ever appeared in the series teaming up to fight Darkseid, but for sheer audacity, it's worth a read even if you don't know who anyone is.
It's a little hard to keep recommending because you say you want suggestions noted as single issues rather than trades, which is the easier way to get into comics these days.
If you were willing to try trades, I'd simply suggest start with the first collection for any character you are interested in and keep reading until the stories no longer work for you.
But the above individual issues featuring DC's biggest characters are a good start.