Preferences definitely count, though. Mayor Blob was awesome. Strapped with massive amounts of muscle and lard, a powerful consoler and pacifier, and all he needed to be happy was coffins. Not like I ever export those anyway, but I'll certainly be building 'em.
My current mayor is a vampiress. She's locked away, obviously, but everyone seems to like her even though they've never met her. She also demands that I make shields practically nonstop.
Fortunately, her favorite metal is copper. It just so happened that I have half a dozen artifact copper armor pieces in my fort, one of which is a shield. I put her in the military, gave her the copper, then sent her into my permanent danger room in her palace at the bottom of the map.
I plan to keep her training until the inevitable death of my populace, at which point I'll release her and pull a Urist, slowly converting all migrants to my own private army of vampires.