I'm creating files to read on a
reMarkable 2 tablet, which allows EPUB files to be
uploaded, but it converts them to PDF internally and the PDF is what it shows on the screen. The PDFs it produces look ... "less than great"?
This page explains that if you manually convert the EPUB to PDF before uploading it to the tablet, you'll be able to control things like fonts and sizes, line spacing, and margins, and be able to see
exactly what the file is going to look like before you upload it ... since you won't be able to control those things from the tablet itself.
Also, I'm a command line guy. Writing documentation which says "click this link, at the top right corner click this, enter this value, click this, on the next page find the text box labeled XXX, enter this value" and so forth is very tedious to me. My first thought was using "pandoc" to convert the files - this
did work, however the PDF it produced looked even worse than what the tablet generates internally, so I gave in and wrote what you see on the page now.
But then I remembered reading somewhere that Calibre
has a command line tool to convert files between formats, so I found it, and now I'm trying to write a script that I can use to convert EPUBs to PDF, with consistent formatting options every time (and then add that script to the site for others to use, and to modify if they want their files to look different from what I like).
With all that said (hey, you
did ask

) ... for any other device, I agree with you 110% that EPUB is the way to go. Every book in my library
has an EPUB file (except for a few technical books which were
only available as PDF), and for most of them, EPUB is the only format I kept.