Ask HN: Which Udemy course would you recommend?

Just got an email for 75% off one course. I'm thinking about just taking the plunge on something, anything if it means I would really get something out of it.

I'd trust the reviews from HN rather than the general Udemy reviews so please let me know what courses you've taken that you believe have truly been valuable...

(btw, already taken Coding for Entrepreneurs and don't base your answer on interest or skills, just name em and were they excellent?)