I think they all have good looking airflow/light penetration because of your defoliation. You can tell you've nailed the quad because your plants have a very square shape to them from above. When I was trying to figure out how I wanted to train plants I told myself I want 4 plants in a tent and I want each plant to basically cover a 1' x 1' area. That requires the plants being more square and less round. When you pull the 4 main branches out horizontally to quadline you could almost draw a square with the outline. When most people grow plants indoors the side branches are weak and barely get any light and usually get in the way or under-produce. With quadlining you set the frame and then that little stuff now grows in the middle instead of the outside and everything becomes viable and even with little to no junk.
Keep up the good work Magoo!