Im having the same problem.
I was going to post another 24-70 vs 24-105 thread today.
Ive used the search function, ive read nearly all of the threads.
I already know about the tecnical aspects of each lens, but here are a few questions that I would like to know, maybe the original poster can benefit from this as well. Id like feedback from someone whos had experience with both.
First of all, im lazy, I hate swapping lenses. Another thing, I have more than I need right now. Im in the process of getting rid of all of my lenses except for my Canon 70-200 F/4. At the moment I have a Sigma 24-70mm and a Tamron 28-75mm. I like both lenses, but I like the extra 4mm on the wide side better. Both lenses produce great pictures. Why do I want to upgrade to the Canon L versions at this range? Both of these lenses hunt in low light, the Tamron is the worst of the two.
I am still learning flash photography, but ive shot a few birthday parties, and formal parties using my Canon 17-40L and Canon 550ex speedlight. I dont remember thinking that I needed a faster lens, and I was quite satisfied with the results, and so were my clients.
With that being said, I just want to have 1 general all purpose lens. The extra reach and the IS would be very nice, my only concern is lowlight. I will be shooting at a few nightclubs pretty soon, and I will always have a flash. Again, im pretty new to flash photography, would f/4 be ok if im using my flash as a light source? When I used my 17-40L to shoot previous parties, it wasnt THAT dark, like not nightclub dark, but it was dark.
Also, I occasionally do product photography. Both should be able to do the trick, but ive read that the 24-70L is a bit sharper, and has better bokeh. Im not really a pixel peeper, and all of the shots will be post processed anyway.
The only lens I MAY keep is the Canon 50 f1.4.
So, given that info, which lens would you go for?