Nearly all of the northern burbs are fine.
Just about anything around the 275 loop is a reasonable place.
What industry is he in?
Stay out of Cincinnati propper and you don't have to worry about crime. Also Nothern KY is booming, at least economy wise, and there are a few decent neighborhoods down yonder too, but the schools leave a lot to be desired.
Anything north includes but is not limited to:
Sharonville, Evendale, Blue Ash, Landen area, WestChester, Mason, even Fairfield has started coming around.
Commuting here isn't as bad as in a lot of places but it's starting to get that way. He should avoid working downtown if he can, unless he wants to live close to it...
There are lots of decent schools in most of the outer belt areas. But it depends on what you're looking for. It's not easy to say live here or there. Part of it would depend on where he's going to work. If we knew that and more about him and his family, it would be easier to stear you one direction or another
-MD