On a pallet, head folded, legs removed, standing up. Protect edges/corners appropriately, isolate head from the cabinet so as to not damage the head or cabinet sides, shrink wrap then strap to pallet. A heavy duty cardboard wrap to help protect the sides of the cabinet would be nice too, but I doubt that is included.
Safest way out of the 3 you listed.
Keep your fingers crossed your machine isn't handled by a bunch of careless buffoons!!! When the machine is in the center of the pallet, the pallet can be easily moved by hand / fork truck, and the machine shouldn't come into contact with any other freight. If you ship with the legs on, and the machine just sitting in the truck, your exposing all the surfaces / edges of the machine to making contact with whatever else is in the truck. Not to mention if someone decides to pick it up and move it with a fork truck or accidentally backs into it with the fork truck...