I'm starting to when practicing or just drawing for my own fun or whatever, that pen & ink is the most enjoyable out of any tool as of right now. Why? Firstly it's the cheapness of the tool because it could be a mere ballpoint pen or a dedicated fine liner or whatever you have lying around. Secondly, it is essentially permanent so it alleviates any pressure of perfection. And thirdly, it's just very cool to see how it turns out. You can if you know what you're doing range from very detailed drawings to very surrealistic sketches. Like this taken from a book called "how to draw in pen and ink"
To me, this is beautiful because of the limitations of the tool used to its advantage. I'm certainly not against pencil, pencil is perfect for certain types of tasks or desired outcomes, but pen and ink is cool in a way that graphite can't replicate the same thing in the same way.