15-85mm would be a great lens for your application, the 17-55mm would be my next choice. I don't care for the 17-40mm or 24-105mm for 1.6, the first lacks the long end and second lacks the wide end. Besides that the IQ is not that good wide open (in many focal lengths worst than your kit lens) and ok to decent stopped down to f/5.6-f/8, see ISO 112233 crops. IMO the 15-85mm or 17-55mm are much better lenses for 1.6 users.

John.