Flex: kupp, boone, manny or perriman?

General Fantasy Football Talk
#1

0.5ppr, need to choose one flex between these:
Cooper Kupp @ SF
Emmanuel Sanders vs LAR
Mike Boone vs GB
Breshad Perriman vs HOU
Deandre Washington @ LAC

My rbs and wrs are:
Kamara, Singletary
Hopkins, AJ Brown