For commuting I'm partial to converted old rigid MTBs...with drop bars. I also like the 80s Japanese touring and sports touring bikes, threading is usually standard, they typically have nice paint, they're well made, they're versatile and have ample tire clearance. Those bikes have been steadily increasing in value, but they're still out there at good prices if patient.

I think older roadies can make great commuters, but it depends on which one.