The best notebooks I have found that meet both constraints of being cheap but good quality so as to not become frustrating are Muji's notebooks. They have several options in size and also styles between blank, lined, and graph lined and looseleaf or notebooks. They even have these tiny passport sized notebooks that I am trying to get into the habit of keeping with me to write down whatever I need in the moment. The paper quality is actually excellent, and their pens are all I use now as well.
Can confirm, MUJI notebooks are of a decent quality and they can handle fountain pens as well.
In addition to that, I gradually switched to their 0.38 pens of different colors. With fountain pen it was more stylish but impractical for multiple semantic(*) colours. With cheap, light, yet nice quality pens of different colours I can not only carry multiple ones, but have the same set at multiple places.
(Dark blue is body text/drawing, light blue is comment/secondary annotation, orange is action/process/message passing, green is data/metadata flow, …)
I’m a fan of the blank wire-bound Mujis for writing — especially the fine stuff I need to do at 0.30. They look classy and they love the rollerball.
Only downside I’ve found is the paper is thin enough that it’s not a great notebook to have at a bar, where you might get condensation dripping on it, nor for the gym where your hands might be sweaty. For the same reason it’s not much of a sketchbook, but for writing it’s my go-to these days.
I like the pens well enough to keep some around, and I appreciate all the color refill options, but I don’t think they’re “better” in the same way the notebooks are.
From https://www.muji.com/us/feature/whatismuji/: MUJI’s goal is to give customers a rational satisfaction, expressed not with, “This is what I really want” but with “This will do.”
I think half the time I go to a Muji store it's really because the entire space gives me a sense of calm. Making a brand that's inexpensive but still projects a quiet feeling of quality and attention to detail is rare, at least in America.
https://www.muji.us/collections/notebook