I know, for many, this is a well worn topic, but, right now, it's a hot one for me. I've been waiting patiently, stubbornly for a new rebate on the 24-70mm 2.8 II, but the longer I've used my 24-105 in combination with a 70-200mm for events, or my 85mm 1.8 and 135mm 2.0 for portaits, the less I think I really need to spend so much on what I do believe to be a wonderful zoom lens.
See, I have a 9 year old 24-70mm which I no longer can depend on. Had it serviced, it was great, then my wife dropped it, had it serviced again, now it's sub-par. I don't want to spend more repairing it.
I guess if I have a string of low-light events, I'll start craving the 2.8 again, but for outdoor stuff, like tomorrow's big charity walk and celebration, my 24-105 is perfect for candids and informal portraits. For very large (60 people +) group shots, I usually switch to my old 16-35, not only to include everybody, but to avoid the distortion at 24mm on the 24-105mm (which makes people on the edges of the group look fat!).
(And on the other hand, in low light, I do have my nifty fifty 1.4.)
In a nutshell, what I don't like about the 24-105: 1) bad distortion for group shots or when vertical structures are included in my frame, 2) the bokeh can be granular, busy from f/4-f/5.6, especially when leafy branches are in the background. And 3), of course, f/4 can feel like a limitation too.
What I do love about the 24-105mm is the generally excellent sharpness and contrast. The IS is great on mine, which helps account for the sharpness. The range of focal length is fantastic for most situations at most events I do. And it works great for nature hikes too, as the quasi-macro is ok in a pinch, the range is right for good landscapes, and it's light. Bird photographer Arthur Morris says it's his go-to lens when he doesn't have something massive on his 1DX.
I don't know. For mostly people shots, am I really going to be needing the range of 24-70 now? In my opinion, for closer portaits and candids, anything 50mm or lower starts showing distortion on the 24-105, but I hear it is better controlled on the 24-70mm.
I've been assisting several great portrait photographers, top PPA award recipients, and they either use primes or go 24-105 and 70-200mm.
For those NOT weary of this discussion, any input would be great. Thanks, dw2013, for daring to bring this up again!
luciolepri: good insights, thanks!