I currently have a Canon 5D III together with a Canon 17-40 mm L, Canon 100 mm f 2.8 macro, Canon 70-200mm f2.8 II L and a Sigma 150-500 mm. I am considering adding either a Canon 24-105 mm or a Canon 24-70 mm Mark 1 lens. I can't afford the Mark 2! Which one of these would be preferable?

! how about the tamron 24-70?
