> Very few of these work as ebook (Kobo) for me. The formatting of code is poor and diagrams unreadable. Prefer paper or PDF (but read on a computer or tablet without network).
My ancient (2011) Kindle is borderline useless for technical material but the iPhone app renders diagrams and equations acceptably well (my experience, of course). The small form factor of the phone is helpful too - more desk or table space for notebooks. Mind you, I make heavy use of app limits and downtime so its not the distracting experience of typical smartphone use.