The Magik limited series: I just thought it was so cool - her powers, everything she goes through, etc.

Avengers vs. JLA: Just going to sum this one up with one of the coolest scenes in comics IMHO -

Age of apocalypse ftw

The Death and Return of Superman. It’s the story line that got me into comics. I still remember getting excited each week when the next book in the storyline came out. All Star Superman is a close second.

But if you count Vertigo as part of DC, then my answer is Sandman.

Whatever Happened to the Man of Tomorrow? Dare I say the quintessential Superman story.

The Proteus arc of Uncanny X-Men, while not as popularly know as Dark Phoenix or Days of Future Past, the Proteus issues are a trippy and engaging story from the classic Claremont/Byrne era of X-Men.

I have a real soft-spot for Morrison’s new X-Men since that (and the X-Men Evolution tv show) was my introduction to the characters. The art won’t be everyone’s cup of tea, but it has interesting ideas, excellent plotting and character work. In particular I loved the characterization of Jean, Logan and Emma in this run.

DC:

Kingdom Come

Superman for All Seasons

Superman: Red Son

Marvel:

Spider-Man: Blue

Marvel: 1602

Taskmaster: Unthinkable

Special shout out to the X-Statix omnibus. I bought it knowing literally nothing about the characters. It’s got the dimensions of a Manhattan phonebook and I read the whole damn thing and loved it. One of the wildest and weirdest things I’ve ever read set in the Marvel universe. 10 out 10, no notes.