Tabs vs Spaces is a definitive example of a case where I intellectually believe X but socially follow Y.
Well, in the case of word processing, I believe and use tabs. There is no excuse for not taking advantage of tab stops in a word processor.
(Related: I also set proper paragraph spacing rather than hit Return twice)
In code, I believe tabs are the "right" thing to do but I do spaces due to social pressure.
I find intellectually appealing the idea that you use a particular code point (U+0009) to semantically indicate indentation level.
The idea that you use some number of spaces to visually approximate this seems silly to me.
Of course, I've long been passionate about structure vs presentation. Deciding on a certain number of spaces to represent indentation seems like a presentation decision to me.
And yet, despite all this, I use spaces because I've always identified with groups of developers who, for whatever reason, tend to prefer spaces.
And in fact, I will strongly argue for spaces in any Python project.