The look of pure joy on Jakita's face when she gets to fight giant mutant ants. Says it all.
This series is chock full of great moments for artist John Cassaday, some of his works are just beautiful beyond words. How about his depiction of Galactus or the Bleed ship seemingly designed out of Holy Gothic architecture.
The appearance of Adam West's Batman in Night On Earth, particularly because 1) Ellis writes him with obvious affection and respect, and 2) he uses Bat-Female-Villain-Repellent Spray.
Elijah Snow vs. Dracula. Second greatest Curb-Stomp Battle in the whole series. It involves one of the greatest and most creative Groin Attacks in the history of comic bookdom.
Pretty much every one on one fight that Snow gets into. What his Batman level intellect can't defeat, his ridiculous powers can. He takes on Frank Miller's Dark Knight and Adam West's Batman and wins, evaporates a cloud of Sarin gas without flinching, stops a killer with the power to literally shift reality in on itself with a thought, outsmarts a man who has the power to stretch his mind into other people, survived a river that "no one came back" from (twice), froze the Prince of Darkness himself and kicked off his genitals, tracked down a Sherlock Holmes that very much wanted to stay hidden, and, thanks to his ability to freeze anything he wants, can basically defeat anyone who can't survive having their brain frozen.
The Drummer, as a kid, blows up a Four-backed institution, after they had kept him imprisoned and abused for so long.
Ambrose Chase was already a badass in his first appearance, ripping through a horde of Mooks without his powers, but his fight with Kim Suskind tops that.
Elijah:Mister Chase. Remind our guest of where she is.
In the second issue, when the Japanese party reaches a hilltop and discovers the massive corpse of a Mothra Expy. And again at the end of the issue, where it's revealed that Rodan is still alive.
"I know who the Fourth Man is."
Elijah takes out the Four by thinking outside the box. Specifically, he uses simple solutions the Four would never have anticipated. Others see it as an Anticlimax but I see it as the ultimate crowning achievement for Elijah. It fits his style.
Near the end of the series, following the final showdown between Planetary and The Four, Elijah drops a message box onto a hostile and malevolent alternate Earth gearing up to invade our own planet. Elijah then goes off and lists some of the abilities Planetary has uncovered from their massive artifact collection (including, but not limited to, tossing the alien planet into the bleed and wiping the hostile reality from the multiverse supercomputer). Not only is the quote great, but it really brings the whole story back to base—the multiverse supercomputer was found on one of their earliest missions.