I like to read OPM as a kind of Japanese-cynical take on the Justice League. While the JL has people with super powers coming together for the common cause of making the world better, and the Avengers has people with super powers coming together for the common cause of being cops, the Hero's Association in OPM has people with super powers - and a whole lot of pretenders chasing clout - coming together to be salarymen in a massive, inscrutable corporation. The hero's association doesn't empower its members or even promote cooperation among them, instead it pushes them to fight amongst each other chasing personal accolades and slowly crushes whatever enthusiasm they may have originally brought with them into the organization. You may have enjoyed fighting monsters at one point in your life, but if you become an official Hero you will be made to hate it.

Uh anyway I like both shows.