Just a couple minor notes from my experience: 1) Some of the course management software I use doesn't like me typing tab characters. When I want to post sample code into a course page using this software, tabs are either ignored or does something really broken (like post an incomplete file). So, I must necessarily type spaces when posting that code -- and of course, downloading that sample from the page has spaces in it instead of tabs.
Point in favor of using spaces. 2) Tabs are one byte; spaces are one byte; so unless all of your indents are only one space at a time, a source file with tabs takes less memory than a source file with tabs. It's not a significant difference. Very minor point in favor of using tabs. I'm still a spacer myself. -- https://mail.python.org/mailman/listinfo/python-list