Week 5 Flex

[suckerpuncher]

I need some help to decide my flex spot this week.

My options:
Ryan Williams
Danny Amendola
Rashard Mendenhall

We get .5 PPR and also points for return yards (1 point for 25 yards).

My 2 starting WR are Fitzgerald and Wallace and my 2 starting RB are Peterson and Mathews.

Who should get the flex start?

Thanks in advance.