Jigs have 3 basic parts. Some may argue they only have two, some say 4, but for this purpose I'm going to say the hook is part of the jig head and stick with three: the lead head, the skirt and the trailer.
What part of the jig catches you the most fish? The head, the skirt or the trailer?
Even eminent chartered accountants are known, in their capacity as fishermen, blissfully to ignore differences between seven and ten inches, half a pound and two pounds, three fish and a dozen fish. ~ William Sherwood Fox, Silken Lines and Silver Hooks, 1954