I have a very conversational way of writing partially because I do voice to text a lot, so the em dash just “feels” better to me than a semicolon typically.

Agreed: a semi-colon is a bit stop-start, while a en-dash just flows.

I’ve used them, with spaces, for decades. Minus-minus in plain text, and autocorrect reads that nicely.

I sometimes use an em-dash, but mostly in LaTeX: they’re too awkward in plain text.

I use ellipses too …