On visits to Tokyo stationery stores I invariably find myself transfixed by the notebook section. There is endless variety and quality and new items and I want to sample them all...luckily, some of the larger shops like Itoya put them on a stand for that purpose. I just BMOP and write, and the hardest part is deciding which one to get. So, given that most people will need to choose that one single book, I thought it might be useful to explain how I choose the notebooks to stock.
The most important part of a notebook is, of course, the paper. It must be of good quality, meaning that it will not feather or bleed through with ink from a fountain pen. Therefore, it almost goes without saying that any notebook I carry has very good or even superb paper, and that the differences between notebooks are more a matter of taste (paper color, tooth, lines or no lines, etc.) than anything else. So I will not talk anymore about paper, and instead talk about notebook types.
Journals - These are thick and have a lot of pages - usually 200 or more, counting the front and back of each sheet. Because notebooks are typically opened and closed many times over long periods (months or even years) binding quality can be very important. In fact, the best production binding for frequent use is the same kind used in quality bibles and dictionaries, also known as thread binding, Smyth-sewn, sewn-along-the-fold, library binding, and other names. And, aside from strength and reliability, another important trait of thread binding is that, given the right production techniques and materials, it allows a notebook to lay flat when opened, making it easy to write in comfortably.
Any journal I carry will have a thread binding, for both quality and tradition. There are other "adhesive" binding methods such as perfect-bound, notch, double-fan, etc. but those alternatives are geared towards applications where least cost is very important. There's nothing wrong with that; adhesive bindings if done well are fine but they always come with a trade off between strength, durability and lay-flat quality. Only thread binding offers no compromise; it is the gold standard of all production binding methods.
So, in the end, when it comes to notebooks or journals, please choose the binding deliberately, regardless of what that choice may be. I happen to feel that thread binding fits in well with the fountain-pen-and-ink aesthetic - but it's up to you. All I'm suggesting is that if you make an informed decision, you'll have no regrets.
One last thought about journals: There are skilled journal craftsman that do beautiful work with a variety of techniques that usually employ some kind of threaded binding (e.g. Japanese binding). Aside from being finely crafted, they also add value with beautiful leather and fabric covers, gilded edges, personalization, etc. But those are specialty items beyond the scope of my store. One of these days I hope to get something like that for personal use.
Wire-bound- These also have a lay-flat quality, but instead of using them for journaling you might use them for taking notes at work or in a classroom. Thick, sturdy, non-floppy covers are always nice. The wire can get in the way of your writing hand, preventing you from getting full use out of each page, but then these notebooks are informal and the pages can be torn out. When traveling, I organize receipts and other ephemera by taping them into a wire-bound notebook. For some reason I don't feel the pressure of a full commitment when it comes to wirebound notebooks, and sometimes that's a good thing.
Pocket notebooks - These usually have flexible covers and a small page count and you can fit them in your back pocket or slip them into a bag. A good example of a pocket notebook is the Moleskine Cahier (which I do not carry). As for binding method, I prefer sewn over saddle-stiched (stapled). They usually do not lay really flat unless you fold them over the opposite direction, but after that they won't close all the way either. At work I jot notes into a small Life Vermilion notebook while walking the floor.
Ring Binders - The ring binder is great for moving paper within the binder and among binders. Good hardware is essential - you don't want rings suddenly popping open and allowing sheets to fall out. Japanese ring binders, such as those from Kokuyo and Life, have a lot of strong rings (A5 has 20, B5 has 26, and A4 has 30), while US binders have 3 ("three ring binder"). More rings are better for the simple reason that the stresses of holding in paper are spread across more points, resulting in fewer torn holes and no need for those old white bad-tasting donut stickers. The pages are also easier to turn, and you can add dividers or other accessories such as business card holders, photo sheets, maps, and so on. You can't do any of that in a journal or wire-bound notebook.
And a great feature of ring binder paper is that it doesn't have to be in the binder to write on. You can write on loose sheets, and insert them into the binder at where and when you want. There's also no wire ring to get in your way while writing, and of course loose sheets lay perfectly flat. You could say that the ring binder offers a unique process that other bindings cannot.
That’s it. I hope this was helpful, and I’ll try to update this page as other thoughts come to me.