Thanks for posting these test shots. I think that to a certain extent, your photos show how difficult it is to achieve the level of consistency required to form accurate judgements. I looked at the f/4 tests, as this was where all the lenses that you compared were included but where resolution differences would still be obvious.
The 24L is so badly front focussed that you can’t tell much from the photo other than the area in focus looks pretty sharp, except for the extreme corners. The 16-35 is either a bit more front focused than the 24-105, or has big resolution issues in the top right hand corner; given that this corner is the furthest away, I would suspect the former explanation.
Things aren’t so clear cut with the 24-70 II and 24-105; is it resolution or depth of field issues causing some of the loss of sharpness visible? Comparing these lenses at f/4 to the equivalent photos at f/8, I’d say that the 24-105 is just soft (this conclusion fits with others’ testing). As for the 24-70 II… Is the softness in the top right caused entirely by depth of field/focusing issues, or is it a bit soft in this part of the frame too?