The reason I use tabs is pretty simple. It's faster to move around only using the keyboard. It's also faster if I'm changing code that requires reformatting. Finally, when another developer looks at the code, their IDE will render the tabs as whatever its set up for, 2 spaces, 4 spaces, etc. In other words, it adds flexibility. Brace yourself: I use two spaces after the end of sentences too. [1] I am quite the rebel.…
This is exactly why I use tabs and the reason which appears to never get cited in the holy wars.
People who use spaces want to line up their '=' signs, that's fine, but I don't believe it's my position to enforce the amount of whitespace another developer has to use in their editor. It's an accessibility thing, they might have their font size really large because of eyesight problems in which case 8 spaces is going to make reading the code a lot harder.
The fact that Python's rule used to be 8 spaces, then got changed to 4 thereby invalidating old code really showed me how shortsighted it is to use a set number of spaces in a whitespace sensitive language.