Flash: Terminal Velocity
A close tie between Kingdom Come and Flash: The Return of Barry Allen. It cemented my love for Wally West by issue #79!
Hush is my nostalgic choice.
As an adult, my favorites are Waid’s Flash run, Gleason’s Superman, and really anything by Waid, come to think about it
I think it might be a toss up between Dark Nights: Metal, Batman: Black Mirror, and Teen Titans: Judas Contract. They manage to tick all the boxes for concept, writing, and art for me. There are other stories/arcs that I enjoy but normally there is just something keeping it from heading to the top.
One of the most entertaining and exciting continuous series for me was Gotham Central by Ed Brubaker and Greg Rucka and illustrated by Michael Lark, that just had a fantastic Noir street-level realistic feel to it even though it did feature fantastical villains like Mr. Freeze.
Crisis on Infinite Earths, especially issue #7. That issue is the single greatest comic ever written. The scope is epic, the stakes are high, and the George Perez/Jerry Ordway art is THE best I’ve ever seen in any comic book.
All star Superman or death in a family
Both by Mike Grell:
Green Arrow (both the Long Bow Hunters and the ongoing after it)