Can't help it. I like em dashes in works of fiction (e.g., C.J. Cherryh); I also find em dashes improve technical writing (for me).

Sometimes adding spaces around em dashes is not about preference, but helpful due to the font, or the device, you're reading on. At some zoom-levels, for example, an em dash may bump into an italicized word unless there's a bit of extra space.