DBZ's androids are advanced almost to the degree of biotechnology, and possess the ability to channel the same power Goku and others do to produce their energy-blasts and whatnot. Vex? They're metal frames with weird, prokaryotic sludge in them. Their weapons do not POSSESS power, they draw it from somewhere else entirely. So why exactly WOULD the Vex rate on Goku's power-scale? The only ones I can see showing up for him are the Minotaurs, as they possess energy-shielding, the Templar, and Atheon.