MCU Loki is an interesting character because he's a different character in every movie. He's fun as a villain because he has so much fun with it, and he's compelling as a hero because he's so full of conflict. Whatever he is, his charisma always sells it.

Mel probably had the least compelling story in Arcane, but to be fair, she was up against a lot of tough competition. Kind of a pity though. Still, in my opinion, she has the best aesthetic of any character in the show, which is saying a lot.