My preference has always been for the "walk-in" around the wall style.
True, you need room for the two "balloon" loops on each end, but they do not have to be directly across from each other.
Besides not needing any duck-unders, another advantage is that a simple crossover, such as the one near Schenectady in the sketch above, turns the end loop into a reversing loop with no additional space taken up.
You can utilize the center of the the room by creating peninsulas that extend out from the wall.
By the way, the large peninsula with the engine terminal and the city of Mott Haven has since been removed in the interests of creating a work area and simply freeing up more space for moving around the basement. The furnace and water heater are located in the center of the basement, so that area is not really as open as the sketch would make you think. Basement steps are located along the wall at the left.
A new smaller peninsula has since taken up a 5'x8' area near the site of the former turntable.
Jim