"10 fonts that I think most people writing code are using but I really have no idea..." should be the title of this. There's no way to know for sure, but realistically the most used fonts are probably Consolas, Inconsolata, Office Code Pro D and Monospace since these are the default fonts on the likely most used code editors (VS, Atom, Notepad++, Sublime, VSCode, Eclipse). Most vim/emacs users likely change their font from the default.