'Best' is subjective, of course. If you think a pretty well written, accessible textbook coupled with a working, non-trivial but understandable codebase to exa

'Best' is subjective, of course. If you think a pretty well written, accessible textbook coupled with a working, non-trivial but understandable codebase to examine is a good way to learn things, then "Operating Systems: Design and Implementation" and Minix is a pretty good choice. YMMV.