Most Helpful Guy
There's not that many 40 year old guys on this site, so we don't really know. That being said, I'd think that men of that age, like any age, are going to have their preferences. Some will like straight, others wavy, still others curly. I highly doubt there is consensus. If anything though, men do prefer long hair over short more often than not. The curls or lack thereof I don't think really makes that big of a difference.