I bought the 24-105 used and very happy with it. The image quality is similar to my prime quality, performance is perfect and feel solid in my hand. I like close up so the Macro mode is very convenience if no macro lens with me. The IQ at macro mode is decent, but the working distance is shorter than real macro lens.
If you no need Macro, go for 24-105, if you need f/2.8, go for Tamron something like the 24-70. I think the majority complain is about the price!