The title of the most powerful in DC Comics can be debated. Characters like The Flash with his speed force or Wonder Woman with her divine abilities could also be in the running. It really depends on the context and the specific storyline.
It's hard to say for sure, but many would argue that it could be Superman. His powers are almost limitless - super strength, flight, heat vision, etc. In a crossover, he would be a force to be reckoned with against most Marvel characters. However, characters like Thor with his godly powers and the ability to control lightning could also give Superman a run for his money.
It's hard to say for sure, but many would argue that it could be Superman. His super strength, speed, flight, and heat vision are incredibly powerful. He has been shown to be able to move planets in the DC universe. In a crossover, he could be a dominant force, but he also has weaknesses like kryptonite that could be exploited.
Lucifer is incredibly powerful in DC Comics. He's often depicted as one of the most formidable entities, with near-omnipotent abilities and a vast range of supernatural powers.
Icon is considered a significant force in DC Comics. His powers include enhanced physical attributes and the ability to project energy. These powers make him a formidable character, but his strength can vary depending on the storyline and the context.
One might argue that Franklin Richards would be the most powerful in a 'Secret Wars DC Marvel fanfic'. He has the ability to create entire universes. This power dwarfs many of the individual strength - based powers of the DC and Marvel heroes. But if we consider raw combat ability, someone like Thor with his godly strength, lightning powers, and combat experience might also be a top candidate, especially when facing off against characters like Aquaman or Green Arrow from DC.