What about "whatever you're using"? It probably doesn't seem well thought out, but is there any other answer? Personally I don't care. I use spaces in Python because of pep8 and tabs in PHP or JS depending on whether or not the file is using tabs or spaces already. Sometimes I realize I checked in a file to git with tabs instead of spaces so I go back and run a find and replace to match indentation. Is that so wrong? Shitty question IMO