These two niggas have the ill prep time. The Batman has the where with all to defeat every member in the JLA. His skills of deductive reasoning are second to none. The Batman knows your moves and has a successful counter for it. On the other hand, Ozymandias, (The World's Smartest Man,) succeeded in his maniacal plan to save the world from a nuclear holocaust under the guise of a faux alien invasion in which half of the residents of Manhattan were sacrificed. To execute this plan, Veidt killed The Comedian when he learned of his plan. He set up Rorschach, allowed himself to be shot, then killed the would-be assassin, right after the shooting, then illest shit of all, Veidt neutralized Dr. Manhattan, a being who transcends space and time.
The Batman is my absolute favorite character in comic book fandom, however, Ozymandias prep time>>>>> The Batman's, therefore Veidt gets the victory.