Vibrator. Keeps the women-folk happy. Therefor, everybody happy.
the hoverboard.
OK, for the win (possibly), the Antikythera computer. 2000 year old computer that accurately predicted astronomical movements.
Bridgeport milling machine, no question.
http://www.mdavisgrp.com/media/items/Bridgeport_Milling_Machine_SN_J2847080.JPG
The camera.
(pictures of naked ladies!)
Like the other riders who posted here, I’m going with the machine that has given me the most pleasure between my legs: a Vespa GTS 250 Super. When the weather’s too shitty to ride, I just stand out in the garage and rub against it.
Is that how they spell Gibson Les Paul Custom where you come from? 
My Vespa GT200. I love everything about my scooter, and I plan on enjoying every riding moment left in me. I would marry it, if I could.
I’ve always thought I’d like an organ with an Ira Dei stop, myself.
I would say that the bicycle just has a certain elegance to it that other machines lack.
Computer chips are elegant too, if you look at their schematics they’re like works of art. In fact, I have a framed picture of a computer chip schematic I got at a garage sale.
Besides from my scooter, I would have to say that the Schwinn Stingray - banana seat and ape hanger handle bars bicycle that I had when I lived in Lima at age 9, has to be my other favorite machine.
I’m going to go with Robby The Robot.