I love the ergonomics of hard bound engineering notebooks. The cost is more than I'm willing to pay for the pedestrian kind of notes I take, though.

I got a few of them, partially-used, from a canceled project and I really enjoyed using and carrying them.

I just use composition notebooks which are like $1-$5 depending on the quality, store, sales, etc. That's also what we used as a lab notebook in chemistry class when I was in high school, which follows a similar discipline, so to me it's fitting.