Morris or Colston at flex

[lilcoltsboy1888]

who do I start at my flex, Maruqes Colston or Alfred Morris? I feel like Colston is the safer choice while Morris has more upside but not sure who to play

My Lineup (10 team ESPN Standard Scoring)
QB- T Brady
RB- J Charles
RB- D Martin
RB/WR- E Decker
WR- A Green
WR- V Jackson
TE- R Gronkowski
D/ST- Bengals
K- M Bryant

BENCH
WR Marques Colston
WR Alshon Jeffery
RB Mark Ingram
RB Ryan Mathews
WR Titus Young
WR Randall Cobb
RB Alfred Morris