Hi usf, the 24-70 and 24-105 are excellent lenses! I have and use the 24-105 frequently with great results. I have not used the 24-70, but go to any photography site and you'll read the praises of this lens as well as the 24-105. IQ for both lenses is top notch. They both focus fast and accurate. The 24-70 has 1-stop advantage at f/2.8. However, the 24-105 has a much more useful FL range and IS. Myself and anyone else who has purchased one of these lenses has been at this descision point. Personally, the FL range and IS are more valuable to me as general use walk around lens than the 2.8 aperature provided by the 24-70. I use fast primes for my low light or less DOF needs. You should also consider what other lenses you are possibly interested in buying in the future. This way you can have a more complete and planned kit for YOUR needs. For example, a lot of people will do the 24-70/70-200 combo or, as I have, the 10-22/24-105/100-400 combo.