Fantastique. 110%.
It was kind of the first custom deck with animation incorporated into it's design. Sure, there were trick decks, but none really had the full animation back the Fantastique had. Plus, it had a lot more going for it. There were more animations: The eyes of the bird, the tree out of the hat, the bicycle, the band members, the pulleys, and the moving halves of the woman. The Mechanic deck was just... gears.
Plus, let's not forget the overall design as a whole. The artwork on the jokers, ace of spades, and box for the Fantastique was phenomenal. The silver tied in the deck's design together, and gave the deck an awesome shine when you fanned it in the light. It seems the Mechanic deck had much less thought put into it. The theme of the Fantastique was also a lot more original, interesting, and inspired than a Machine themed deck.