I use a fountain pen every day.
I write my journal with a black Lamy Safari with De Atramentis Document Brown ink.
I sketch with fountains pens, usually a Lamy, and always using Platinum Carbon Black ink. It’s the best for ink and watercolor sketching. I dries fast and is permanent.
My favorite for both writing and sketching is the German made Lamy. I can be hard on a pen as I have been known to drop them while sketching. The Lamy has easily interchanged nibs to I can just replace one I’ve damaged without replacing the entire pen.