I like paper notebooks. They have pros and cons like all tools do, but I've never been able to go fully digital with notetaking or jotting down random ideas. I've tried lots of different notebooks over time, and the right price to performance ratio for me has been Midori MD Notebooks. (Note, no links on this page are affiliate links. They're just my preferences.)

The notebooks are effectively refills that go into a cover. They still have a cardstock outer shell of sorts, but the binding is exposed without an outer cover. I think this makes them cheaper than most other notebooks with high-quality paper (somewhere in the ballpark of 6-12 USD depending on size and type). They also have an incredibly large variety of other paper products like memo pads, sticky notes, and letters/envelopes.

They're not without their cons, but I haven't found any of the cons to be a major problem for me. Ink shows through a bit on the other side of the page, but I still use them with pens, and it's not bad enough to be frustrating. Additionally, some of their lined notebooks have a single dark line in the center of the page to divide the page in half. That's fine if you want the page divided in half. It's kind of strange, otherwise.

Notebooks

Midori sells lots of different notebook varieties. The two I use all the time are the A6 blank, and the A5 dot grid. The former is for quick-and-dirty notes, and the latter is for things that are a little bit longer that I expect to refer back to. Both of these have more than 80 pages, so they're much thicker than something like a Field Notes notebook.

For something more similar to Field Notes, I found recently that they sell "light" versions in an A6 and A7 size. I don't have as much experience with these, but I'm going to try them out soon. Be aware that the A7 size is very small.

Covers

If you use midori notebooks, it's good to have a cover to add a little bit more protection. You can either spend a ton of money on a fancy leather cover, or you can buy a cheap cardstock cover. The cardstock covers are what I use, and they're significantly more durable than I expected.