First, heck of a draft for a 12 team PPR. Nice to have these tough decisions.
I really like Sproles in PPR so I leave him there.
I do like Garcon getting balls from RGIII over Blackmon getting them from Gabbert. So I would make my WR2 Garcon and then you decide between Blackmon or Jennings for your felx. I think it's a toss up but the tie-breaker is to put a RB in the flex vs a WR. So keep Jennings in at Flex