lol adding to the discussion, 24-70L and 24-105L are actually complementing lenses rather than competing... but of course at our budget we can usually only afford one.
went through the same dilemma as you and ended keeping my 24-105L. from my hands-on experience, heres my opinions..
24-70L
pros:
1. f2.8 is invaluable in low light conditions, its the biggest thing i miss about it
2. at f4, the sharpness is simply stunning... beats 24-105L slightly in the center and by a long shot at the corners. (f5 onwards not so obvious)
3. aesthetically and status wise, 24-70L wins... haha
cons:
1. no IS plus heavy weight, gives me less keeper shots at slow shutter speeds compared to 24-105L; 24-105L gives sharper shots cos of handshake reduced, but has more motion blur
24-105L
pros:
1. love the IS especially on the tele end, and in low light... handholding at 1/13-1/20 is not a problem at all.
2. I do a lot of event photography with flash so dont really need the f2.8 (prime lens mounted on spare body just in case), appreciate the longer reach of the 24-105L to get into the action
3. when I do street photog, the longer reach is also beneficial
4. personally prefer the bokeh of 105mm at f4-5 vs 70mm at f2.8-4
so as you wld have guessed, im recommending the 24-105L! hope this helps
