I use: Oxford Black n' Red A5 Matt Casebound Hardback Notebook, and UM-153S Signo Impact Gel Pens. I get through one of those notebooks per year on average.
Edit: https://rwmj.wordpress.com/2017/11/24/keeping-a-work-noteboo...
I rather have files that I can understand later, and easily grep as a bonus...
(I do admit that crossing done tasks on a piece of paper feels very good.)
That plus a nice fountain pen [Lamy Safari 18.7USD], ink [J. Herbin Perle Noir 7.2USD/30ml], mechanical pencil [Lamy Safari 12USD], pencil leads [Uni Nano Dia 0.9USD/20leads], technical pen [Rotring Isograph 16.3USD], and I've got a nice little setup.
This. I never enjoyed drawing diagrams in Inkscape, though my boss swears by it.
I’d much rather draw with pens on paper and then digitise by scanning.
I've found that using a text editor that supports code folding, and following a markup language that enables the text editor to automatically set fold points, helps navigate log entries more efficiently.
I also use a notebook to jot down tasks, but when a job requires a high number of different unrelated small tasks that are completed rather quickly I've found that a physical notebook actually makes the process very inefficient.