I started with the 35 1.4L MKI, which I replaced with the 35 Art.
I sold the Art for events to have the 24mm, the telerange of 70mm is nothing shocking.
In difficult situations sometimes the 24-70 focusses on people in the background after recomposing strange enough.
I read once there could be some sort of problem with the construction of those older lenses.
Now that I have the 24-70 MKI, I miss the 35 1.4 bokeh & sharpness of the prime.
On the other had, I did a Miss election shoot once with about 20 girls, with my 24mm I had the whole group in the picture, a friend photographer had only 28mm and didn't have the group in the picture and couldn't back up. Also for fashionshows the 24-70 is my widedst.
But I think I will quit those events and concentrate more on modelshoots.
For this I have allready a 50 Art (close to the 35Art), also a reason why I sold it
The 24-70 2.8LII will probably be the best for me, although it doesn't have the 1.4 bokeh... time that this one drops in price secondhand will be long...