Really there isn’t a secret magic brush setting that’s gonna make your stuff look good. It’s best to play around with any you think are cool until you find ones that you feel comfortable using. Plenty of people make hella awesome stuff with just the default round brush with pen pressure (and it’s what I use like 70% of the time).
I choose brushes based on what I need. If I want to throw in some grit or texture, I’ll pick a brush that’ll give me rough marks. If I want neater bits of colour, I’ll pick something smooth. I cycle through a lot of brushes and often forget the exact ones I used each time (which is real dumb of me whoops).
Keep experimenting with stuff until you find what works for you.