I used to be a tab freak -- I would always use tabs to indent my source code, and if I saw any spaces, I would instantly do a regex search/replace to replace all leading spaces with tabs.
...until I realized that I hadn't noticed the presence of a lot of the spaces in some files, such that they opened up inconsistently in different editors (e.g. Notepad++ vs. Emacs vs. Visual Studio).
What are good reasons for why one is better than the other in general? Is either one generally known as better practice?