Black Adam is superior to The Big Red Cheese.
1. For starters, there is no confusion, legal or otherwise, about what his name is. As opposed to the former Captain Marvel now Shazam aka Billy Batson.
2. He fits into the modern DCU far better Captain Billy ever did. There is definitely a greater place for rampaging, imperious anti-hero on Main Earth than there is for a child who turns into a hodgepodge of different religions (Greek/Roman/Jewish) champion.
3. Black Adam can coexist alongside Superman, Wonder Woman and the other major alphas without stepping on any of their toes. He has the Egyptian pantheon to himself (the Hawks just need to go and stay fully Thanagarian in origin).
4. He is more popular than his archenemy. And by a considerable margin (esp considering the name thing). This really only happens with team villians, i.e. Deathstroke and Teen titans, Dr. Doom and the F4, not with solo villains: joker is not more popular than Batman, Luthor is not more popular than Superman, Cheatah is not more popular than WW. But Black Adam is more popular than Captain Billy.
5. He is the only villain getting his own solo DCEU movie, on top of the other one with Captain Billy in which he also stars.
6. Dwayne "the Rock" Johnson. He is the Live-Action Black Adam. Perfect casting. No such ready-made lightning in a bottle casting exists for Captain Billy.
, either as Shazam or as Billy Batson.
7. Black Adam can have a perfectly healthy sex life. Captain Billy cannot due to his being both underage and full-grown at the same time.. Black Adam can have a spouse and children (Isis and Osirus). Captain Billy cannot (see Stargirl).
8. All his reprehensible villainous misdeeds can easily be hand-waved away, a la current Harley Quinn.
In conclusion, DC should push Black Adam as their answer to Marvel's Hulk: destructively awesome, but not evil. He will sell.
Hail Black Adam!