The above are the correct efficient designs. The people who come up with all the ship designs in most of the sci-fi stuff always add some sort of sleek and aerodynamic shapes, which in an airless environment, it just so much waste of potential space. As long as you can properly account for inertia, and slow down and speed up the ships without causing the crew to stroke out, a giant cube is always the way to go.
Resistance is futile.
Resistance is futile.
We found the Borg!