One of each, if able to play WW on turn 4 you'll have perfect knowledge of the last card in your draw pile.
In the long run you might (ahem) wish you had more Wells and not the Silver but starting with exactly one Silver is the correct move on most boards.
I have imagined a board, that you may only want to buy WW, Witch, silver and gold. There is no village, and you don't want to draw WW when you play witch. Will you start with silver/silver in this board?
Harvest /Library / Merchant Ship /Sea Witch /Witch
Fortuneteller / Sea Chart / Wishing Well / Bureaucrat / Duke