Since we are presumably talking about the 2017 Continuum, I'd have to go with Glomgold hands down. In the episodes I've seen, he's a very funny character who probably gets bigger laughs out of me than any other DuckTales 2017 character. He also has an interesting backstory that highlights both his pettiness and his determination.
I agree. Magica's a close second, but suffers from the fact that her motives are way too vague — it's clear that there's a reveal waiting to drop at some point in Season 3 that will recontextualize it all, but in the meantime, it hinders the character somewhat.
On another note, though, Brix, please pay more attention to your spelling. I wouldn't go harping on about things like "Don Carnage vs. Don Karnage", but… seriously? “Da Spell”? “Villan”?