Cosmic Boy

In the last decade or so, Martian Manhunter has really been incorporated into the Superman mythology via comics and media. He was tasked by Jor-El to watch over Kal-El on Earth in the comics and this was reinforced in the Smallville TV series. That's been continued by proxy in the new Supergirl TV series where he's a major part of the story having done essentially the same thing for Kara (and likely Kal as well, though this hasn't been shown). 

From my perspective, the Fourth World books are absolutely Superman family titles and the whole run belongs in any Superman collection. They're also some of the best art in comics' history. 

These days, I also consider anything specifically Martian Manhunter to be a Superman family title as well.