Best Single issue in Comics (one from each company)

just as it says, what is the BEST single issue in comics, NO Story Arcs, NO Graphic Novels, NO Writer Runs. just single comics

if its part of a run, or story arc, you treat it as if the rest of the story doesn't exist, as if someone picked up the issue read it, and put it down never reading the rest

judge based on Cover art, interior art, writing et cetera.

for DC Justice issue 4 (read it by itself, its triumphant)

for Marvel Iron Man/Captain America Casualties of War (WOW this sums up the internal conflict of the entire mega crossover event, and it portrays both characters beautifully, and attempts to explain Iron Man's reasons for supporting metahuman slavery)

(honorable Mentions Daredevil issue 26 from Bendis run, the Last issue from Lex Luhtor Man of Steel and Green Lantern issue 9 from Geoff Johns run I seriously considered both of these before I passed on them, and they are great on their own, one sets up a great plot, the other wraps up previous conflict. and Lex luthor explains the character throughout Superman comics (or at least most of them))

(I will not post indie comics, because I haven't read enough)