24-70:
-Faster
-Smaller
-Lighter!
Smaller??? Lighter??? That is definitely NOT the 24-70 f2.8L mark i that I owned a little over a year ago!
I had the 24-105 for a couple of months and figured I'd give a try to the 24-70. Used it for a wedding (as guest) and found that although it was a stop faster, the lack of IS caused this old geezer problems...especially at slower shutter speeds on my 60D (no surprise, really). The weight was another problem for me. It's not called 'the brick' without reason. So I sold the 24-70 and kept the 24-105.
Since upgrading to the 5D mark iii, f4 is no problem whatsoever these days...neither is f5.6 or f8 in dim light. ISO 6000 solved all my slow shutter speed problems!
As for the 24-70 mark ii, however, all I've read was how super sharp it is, etc. But even with improved glass and less weight compared to the mark i, I'll stick with my 24-105. For me, and many others, the 24-105 is a great walk-around lens. Perhaps 70% of my shots are with that lens. It would also give you a great focal length 'overlap' with the 70-200, to reduce the number of lens swaps needed.
If I could only own 1 lens, it would be the 24-105, hands down.