What is it about Thor that makes for the best Marvel movie villains? Loki is hands down within the top three next to Hela and Killmonger. He's relatable, while also being completely unrelatable. We can all understand how upsetting it is to have father issues, but also, he's a complete maniac who likes hurting people. Hela is awesome just because she's super powerful and badass. Not that Loki isn't, but Hela walks in a room and you think, "well, I'm dead."
Hela is literally the Goddess of death and the executioner of Asgard. That's not a position you get by having a kind heart. I'd be a terrible executioner. I'd feel so bad about killing people that I'd do it really gently, which is only worse. What happens when you get fired as an executioner? Are you executed?