Black Adam is one of the most brutal fighters in the DC universe, while also being one of the most over-powered. On the other hand, the Hela portrayed in the recent film is a joke compared to her comic book counterpart, who is feared and respected by the Asgardians for pretty good reason.
Since Adam cannot be instantly killed by Hela's command (him being immortal and all), this would be a more hands on battle between a man who surpasses Superman, and a woman who can wield the dead. It's important to note though that Hela is no slouch in a hands on fight. She's drastically stronger than even the Hulk, can utilize high level magics, is a master of swords, is nigh-invincible, and can manipulate her body to other planes of existence where she can still interact with this one while remaining invincible. There's solid reason why she's the queen of what's essentially the Asgadian hell.
I'm giving it to Hela.