Green Lantern (All 7200+), The Flash Family, and the Teen Titans are my favorite groups in comics, and it’s no coincidence that Geoff Johns has had fantastic runs on each of those books.
Geoff Johns loved writing for film and comics so much that he straight up called Richard Donner’s office for an internship and got it after a single conversation with Donner. While working with Donner, he met DC Comics’ New York staff and started writing there occasionally, working on the book Stars and S.T.R.I.P.E., co-writing JSA, revitalizing the Flash (his favorite character), and relaunching Hawkman and The Teen Titans. Johns is also responsible for returning Hal Jordan back to life and creating an even larger scaled universe than Green Lantern already had, retold and consolidated Superman’s origins, brought back Barry Allen in a story that wonderfully showcased the entire Flash Family, became DC’s Chief Creative Officer, and wrote Flashpoint, the story that transitioned the DCU into the New 52.
There’s a reason Johns is trusted with so many characters. He’s very good at finding what makes a character who they are as a person and reflecting that in their heroics/villainy. His work with group titles has shown how much he values personal interaction in and out of the action, which serves to make the characters feel more like real people. He takes into account their histories and the work other writers have done with the characters.
He’s a comic fan writing comics. And writing comics well.