I own both and owned the 24-70 first. The 24-105 came with a camera I purchased for my wife.


Now, I shoot weddings where a necessarily low f-stop isn't required but appreciated but also I shoot indoor sports where every f-stop counts


Overall- 24-105 due to price and additional 35mm reach.


I find more and more that my wife and I prefer to use it. In fact, when I purchase additional 5D MKII's in a few weeks I am ordering another 24-105.


It is much lighter to use for wedding and has been my 'goto' lens in that situation.


Now when I shoot indoor sports I am finding that I am using a different lens - the 70-200 f 2.8 IS or my 85 1.2. (basketball, gymnastics, etc)


I am finding the 24-70 lens is more and more being either left in the bag or at home.


I'm currently using the Mark III D with the lenses.


Will I sell the 24-70? Probably not but the thought has crossed my mind.