Oh yes. What other software allows you so much to make it your own? Yes, I know the yak shaving argument etc. But what's the fun in opening up some computer/OS/software that looks and feels exactly like everyone elses? An Emacs (and vim) setup is something you can actually have a discussion about with someone else.
KDE, various window managers (i3, awesome, xmonad,...), the Linux kernel (there's so much stuff you can configure through sysctl alone, and that's just 1 single customization facility), SystemD, your shell (whether it be bash, zsh, csh, ksh, or something else), and the list goes on.