The 24 L has MUCH less distortion where the 2470 II is frankly a dissapointment. That is on of the reasons I bought it, but serious AF issues and, as you say, I found my favorite lens in the 35 L as it is epic in (almost) every way, and why I am waiting so bad for the mkII to show up...
I did not notice much of a difference to be honest between the two with distortion... I know the prime is better, but lightroom can very easily correct if need be. I rarely even corrected the Samyang 14mm with its crazy mustache distortion unless it was required! So I am quite tolerant to most distortion unless it takes away from the final image where I will correct it!
Are you saying the 24-70 II had AF issues or the 24L? Because the 24-70 II is probably the most accurate, well performing AF lens I have ever used. The 24L II was very hit/miss, due in part to the f/1.4 aperture I would assume.
Correcting distortion kills microcontrast and going back and forth with correction in LR reveals that much of the pop is lost, again, others may not care about that at all, but I do, and correcting corners will make IQ in the corners worse due to stretched pixels.
I meant the 24 L has AF issues and it's not related to the large aperture, I had two copies replaced by Canon due to EXTREME inconsistency, my third was better, but not even close to the 35 L. And I am not the only one.
The 2470 II AF I agree with you is one of the best ever.